Edit a page canvas
Each
page has a unique canvas, with independent canvas size, color, and
image resolution.
Select a page from the Pages panel or the pages pop-up
menu at the top of the document window.
Select Modify > Canvas > Image Size,
Modify > Canvas > Canvas Color, or Modify >
Canvas > Canvas Size.
Make the changes. These changes can also be made using the
Properties panel when the canvas for a page is selected.
To apply the changes to only the selected page, leave the
Current Page Only option selected. To apply the changes to all pages,
deselect the option.