Office in the Mac is AWFUL about this.

By default, it saves to a OneDrive you never asked for and can never find. You can't permanently change the location of your saved documents-- just change it once, and the setting stays "forever", maybe, until a software update fucks it up for you again.

Auto-save is disabled if you're not using OneDrive.

Nobody asked for OneDrive. It makes it a goddamned nightmare to find your files. I was trying to make it easy for my partner to save their files to the same location every time, make it easy to find in the Finder, make it easy for mailing attachments. No such luck.