How to fix file permission error in Word for MacBook Pro

This problem pops up intermittently, usually at the most inconvenient times.

When trying to save a newly written, plain vanilla Word document (or sometimes, when trying to save an updated version of an older document), it responds "Word cannot complete the save due to a file permission error." I am the sole user of this Mac. The file isn't read-only. I am running version 16.82 Word for Mac, and Monterey version 12.7.1.

[Re-Titled by Moderator]