Editing a PDF in Preview: what it can change and what it cannot

A contract needs one paragraph corrected. A scanned set of statements needs two pages dropped and one inserted. The file is already open, Preview is already the default viewer, and the Markup toolbar is one click away. Whether that is enough depends on a line Apple draws plainly in its own documentation and most search results blur: Preview rearranges and marks up a PDF, but it does not rewrite the text that is already inside one.

Knowing which side of that line a task sits on takes about ten seconds, and it saves the twenty minutes usually spent hunting for a hidden text tool that does not exist.

The line Apple draws in its own guide

The Preview User Guide opens its annotation page with the limit stated first: although you cannot edit the text of a PDF in Preview, the markup tools are there to provide feedback or write something down. That is not a hedge. It is the shape of the app.

The Markup toolbar holds Text Selection, Rectangular Selection, Redaction Selection, Sketch, Shapes, Text, Highlight Selection, Sign, Note, and the style controls for shapes, borders, fill and text. There is also a Draw tool, which Apple notes appears only on computers with a Force Touch trackpad, where pressing harder gives a heavier line. Rotate Left and Rotate Right sit at the end.

The tool called Text is the one that trips people up. It adds a new text box on top of the page. It does not open the sentence underneath for editing, and nothing reflows. Type a corrected figure into a box placed over the old one and the PDF now contains both numbers: the visible new one and the original, still sitting in the text layer where a search or a copy and paste will find it.

Apple documents exactly one tool for taking text out of a PDF, Redaction Selection, and describes it as selecting text to remove it from view. The redaction can be changed while editing, but once the document is closed, it becomes permanent. A filled rectangle drawn with the Shapes tool is not documented as doing any of that, so it should never be treated as a redaction.

One more detail on the same page is easy to miss and matters for anything going outside a company. If the PDF has a table of contents, entries in it that link to redacted text are not removed.

Pages are where Preview is genuinely strong

Page surgery is the part of PDF work Preview handles as well as anything, and it is almost entirely drag and drop.

Insert a page with Edit > Insert, then Page from File or Blank Page. The new page lands after the current one, so select the page that should come before it first. The same thing is available from View > Thumbnails using the button at the bottom of the sidebar.

Delete a page by choosing View > Thumbnails or View > Contact Sheet, selecting the page, and pressing Delete. Apple flags the side effect directly: when a page is deleted, all the annotations on that page go with it. Reordering is dragging thumbnails to a new position. Moving pages between documents is dragging thumbnails from one PDF window into another, with both in Thumbnails or Contact Sheet view. Dragging thumbnails from the sidebar out to the desktop creates a new PDF from just those pages, which is the fastest way to split one file without a separate tool.

Combining works at either scale. Individual pages can be added from one PDF to another, or the entire contents of two or more PDFs can be merged.

Crop hides content, it does not delete it

Apple's wording on cropping is precise and worth reading twice: you can crop a page of a PDF to hide content. Hide, not remove.

The mechanics are simple. Show the Markup toolbar, select the portion of the page to keep, and click the crop control. Tools > Show Inspector gives the dimensions of the selection in the unit of measurement chosen there. Undoing immediately is Edit > Undo Crop, and undoing later means File > Revert To > Browse All Versions to find a version from before the crop.

That undo path is the tell. A crop that can be reversed from the file's own version history is a presentation change, not a deletion. For a header trimmed off a draft, that is fine. For a cropped PDF leaving the building, it is a reason to export a fresh copy and check what a reader can recover.

Forms, signatures and the AutoFill most people never find

Filling a real form field is direct: click the field and type. When a PDF will not accept typing, the documented fallback is to add a text box from the Markup toolbar instead, which is the difference between a form with fields and a flat scan that merely looks like one.

Preview also has enhanced AutoFill for PDF forms. Clicking the AutoFill Form button above the PDF, or clicking a field and then a name in the pop up menu, fills names, addresses and other contact details from the Contacts app using your My Card. Apple notes that not all PDFs support this.

Signatures can be captured three ways: drawn on the trackpad, held up on white paper to the built in camera so the signature sits level with the blue line on screen, or signed on a nearby iPhone or iPad with a finger or Apple Pencil. The device route depends on Continuity system requirements being met, which is the same plumbing behind handing work between machines. Whether you can also reach the Mac itself from an iPhone or iPad is a separate question with a separate answer.

Saving is the step that decides whether marks stay editable

This is the part that causes the most confusion between two people passing a marked up PDF back and forth, and Apple states it in a single note.

To keep annotations editable later, save with File > Save, File > Export, or File > Export to PDF. Automatic saves also keep annotations editable. To flatten annotations so they cannot be edited, choose File > Print, then Save as PDF.

So flattening is a print operation, not an export option. Anyone who has watched a client drag a highlight out of position, or seen a reviewer delete someone else's note by accident, was one Print away from avoiding it.

Going backwards is File > Revert To > Browse All Versions, which works on PDFs the same way it works on other documents.

Passwords, permissions and file size

Password protection lives in the export path. Choose File > Export, click Permissions, then select Require Password To Open Document and enter a password twice. Separately, the checkboxes there control which actions, such as printing or making changes, are allowed without the owner password, and the owner password is set in the same panel. Apple notes twice that changes take effect the next time the PDF is opened. After an owner password exists, File > Edit Permissions reopens the same controls.

The reverse situation appears in the guide's troubleshooting section. If text cannot be selected or copied, either the Text Selection tool is not the active tool, or the PDF requires a password that has to be entered under Tools > Show Inspector.

For size, File > Export offers the Quartz Filter pop up menu with Reduce File Size, plus three checkboxes: Create Linearized PDF for faster loading in browsers, Optimize images for screen, and Save images as JPEG. Apple's own caution applies: the compressed PDF may be lower quality than the original, and the result varies with the options chosen.

The review tools that are not really editing

A second group of features sits beside markup, and mixing the two up is part of why the question keeps coming back.

Highlight, underline and strikethrough attach to selected text rather than floating above it. Select the text, click the arrow next to the highlight button, and choose a colour, an underline or a strikethrough. There is also a highlight mode: click the highlight button so it turns grey and every later selection takes the chosen style automatically. Removing one is a Control click on the text, then Remove followed by the name of the item. View > Highlights and Notes collects every highlighted passage in the sidebar, which turns a marked up document into a review list.

Notes and speech bubbles carry the comment itself. A note is added from the Markup toolbar and closes by clicking anywhere on the page, and its colour changes with a Control click on the closed note. A speech bubble comes from Tools > Annotate > Speech Bubble and resizes by its blue handles. Both appear in the same Highlights and Notes sidebar, and a note is deleted by selecting it there and pressing Delete.

One detail matters for anything sent outside a team. The note author name defaults to your macOS login name. It is changed under Preview > Settings > PDF in the Name field, and it can be dropped entirely by deselecting the option that adds the name to annotations.

Bookmarks round out the reading side: Tools > Add Bookmark, then View > Bookmarks to get the list. Nothing in this group alters the page content, which is why all of it is reversible and why the redaction and crop tools deserve more care than any of it.

Where Preview stops, and what the next step is

What you want to do	Preview	Where to go instead
Insert, delete, reorder, split, merge pages	Yes, by dragging thumbnails	Nothing else needed
Change a sentence already set in the page	No	The source document, or an editor that rewrites the PDF content stream
Cover a figure visually	Yes, as a shape annotation	Redaction Selection if the text must actually go
Remove text for good	Redaction Selection, permanent once the document closes	Reopen and search for the text to confirm
Fill a form	Yes, fields and text boxes both	Nothing else needed
Flatten marks before sending	Only through File > Print, then Save as PDF	Nothing else needed
Apply the same export to 300 files	No	A script run from a terminal
Compare two revisions of one PDF	No	A file comparison tool

The two rows at the bottom are the ones that change how a day is spent. Preview is a one document at a time app by design, and every setting described above is chosen per file in a dialog. That is fine for one contract and unworkable for a folder of three hundred statements that all need the same flattening, the same password, or the same size reduction.

At that point the bottleneck stops being the PDF and becomes the layout of the desk. The folder is in one window, the terminal is in another, and the file being checked is in a third. Finder replacements differ mostly in whether they close that gap, and a side by side look at Mac file managers is the quickest way to see which ones put a shell next to the folder rather than in a separate app.

What to change first

Sort the task into one of three buckets before touching anything: page order, marks on top, or the text itself. The first two are Preview's job and take minutes. If the task is the text, go back to the document the PDF came from rather than fighting the export, and if the same change has to happen across a whole folder, put the folder and a terminal in one window with Atriens and script it once.