Word File Can't Save

My MacBook is MacBook Pro, 2020 and macOS is Sonoma 14.5.

I have been having this issue for 5 days or so, and I cannot save a Word file after modifying it, even in Save As mode.

Whenever I try to close the file, I get pop-up message says "Do you want to save the changes made to the document", click on SAVE, the file closes once but pops up again. And sometimes changes into Read-Only mode. So, I need to use Save As mode and add some words or numbers to make different files over and over.

macOS was updated after the issue started. I uninstalled and reinstalled Word, contacted Microsoft tech support for this, and got remote support that uninstal and reinstal again, but none of this fixed the issue.

I need help.