page numbering in Indesign

The main purpose for previous and next page numbers is a different. 
When you have a threaded story accross several pages, you can draw a text frame which touches the story text frame and write ”story is continued on <Next Page Number>. This number will update, if you move the next threaded text frame to a different page. 
The same is with previous page numbers for continued threaded text stories. 

Just to add a technical point to JML's excellent answer — InDesign has very rigid, hard-coded handling of page numbering. You either have to use a manual numbering method (flowing numbered paragraphs through designated text frames on the pages) or, as in the method given, omit the numbering frame on any pages you want to do something 'special' with. There is no way to reconfigure the numbering for, say, numbers on both pages of a one-page spread or the like.

But there are multiple workaround methods, at least. 🙂

On the left page of the parent spread, create a text frame and insert the current page number.

On the right page, create a frame that expands on the left page and insert the following page number.

See screenshots. They are in French but I am pretty sure you'll understand.

in the future, to find the best place to post your message, use the list here, https://community.adobe.com/

p.s. i don't think the adobe website, and forums in particular, are easy to navigate, so don't spend a lot of time searching that forum list. do your best and we'll move the post (like this one has already been moved) if it helps you get responses.

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