Hi Warren,
Thanks for reaching out. I understand how inconvenient this can be, and you’re not alone, Word for Mac sometimes doesn’t remember window size correctly. This usually happens because of how macOS and Word handle full screen.
First, exit full screen before quitting Word by pressing Control + Command + F, then reopen the app.
Second, resize the window while Word is open, close all documents but keep Word running, then quit and reopen. This often helps Word remember your preferred size.
Third, if it persists, reset Word’s preferences by deleting the com.microsoft.Word.plist file in ~/Library/Containers/com.microsoft.Word/Data/Library/Preferences/.
Last, check System Settings > Desktop & Dock and enable “Close windows when quitting an application”, and make sure “Prefer tabs when opening documents” isn’t set to full screen.
This is a known limitation rather than something you did wrong, so you’re not alone in experiencing it. If none of these steps work, a third-party window manager like Rectangle or Magnet can help enforce your preferred size.
I hope you find this information helpful. Please let me know if you have any further questions If the answer is helpful, please click "Accept Answer".
Regards,
Carlo