Bookmarks help you move around long PDFs by marking sections you want to find quickly.
If your PDF already has bookmarks, click the Bookmark icon in the left sidebar. A panel opens on the left where you can view and navigate them.
Open the Bookmark in a PDF
Add a Bookmark to PDF on Mac
Delete a Bookmark to PDF on Mac
Click the Expand/Collapse All Bookmarks button (third icon) to show or hide all nested bookmarks at once.
After that, click any bookmark in the list to jump straight to that spot in your PDF.
Expand or Collapse all Bookmarks in PDF