Microsoft Word on a Mac
Overview
Even though I have Administrator Privileges on my Mac Book, I can't save Microsoft Word Files (saved to my Mac from a Portable Hard Drive) ‘back to’ the same Portable Hard Drive.
Background
Successfully downloaded and installed Microsoft Office 2021 on a 2014 Mac Book, running Big Sur. (Note, it's the 'One Time Purchase' Version of MS Office, not the Office 365 Monthly one).
When I open a Word File (from a Portable USB Drive) it opens in Word as: 'Read Only'.
If I want to Save, or Edit, that File, I'm first 'compelled' to click a Banner (that appears at the top of the file) prompting me to save as a 'Duplicate', in order to avoid the default 'Read Only' View.
My issue is that, if (after saving the file on my Mac) I then try to save it back to it's original Folder on my Portable USB Drive (by using MS Word’s 'Save As’ option), I get a Pop-up from Microsoft Word telling me it can't 'over-write' the file's 'earlier version' on the USB Drive. This seems to be because Microsoft Word appears to believe that either:
a) the File saved on my Mac that I’m attempting to ‘Save As’ back to my USB Drive, is Read Only' (which it definitely is not, as it's file Privileges' shows it to be: Read / Write (NOT 'Read Only')
OR
b) …that the ‘original’ version of the file (located on the USB Drive) which I’m now attempting to 'over-write,' is (itself) Read Only’ - which it’s not).
The very same Pop-up Alert, also suggests 'renaming' the file (or 'saving it to another location' on the Drive) but when I attempt to do either, I get a fresh Alert informing me that ‘the Volume’ for the Drive I'm trying to save the file to, is Full or Read Only (NOT TRUE).
As mentioned at the beginning of this Question, I have Administrator Privileges on my Mac Book (so that can't be the problem).
Any suggestions? (Thanks in advance for any thoughts on this weirdness).
MacBook Pro 15″, macOS 11.6