Make sure that "Section start" is set to "New page" (or "Odd page") in the Page Setup dialog box (File | Page Setup). In that same dialog box, also enable either "Mirror margins" or "Different odd and even."

Then, to actually see odd and even pages correctly, you have to switch to Print Preview (via the File menu).

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional