IF the 5 pages are the only pages in the document--then go to 'document setup' to change the page size.
IF the 5 pages are only part of a multipage document (i.e. there are more than 5 pages) then select one page in the pages panel--then choose the custom page size icon at the bottom of the pages panel--click it--a dialog will pop up where you can choose or create a custom page size--then repeat for the other 4 pages
Change page size from control panel only if your workflow allows multiple page sizes in document. Document set up is not changing when you change page size from control panel. If you don't want this conflict in document, change page size only by method suggested by tman69.
If you are fine with multiple page sizes in document, select the pages you want to change by the "Page Tool" (not by pointer tool). Page Tool is the third tool in the tool box. Select the tool and select the pages by shift+click and then change size from control panel.
Thank you. Problem resolved. There's lots to learn.
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