How to restore Time Zone so the change sticks

[EugeneJ]

After the most recent software upgrade, the Windows10 set my time zone to a time zone that is not mine. When I go to Settings > Time & Language > Date & time, the time zone section is grayed out so I cannot change it. At the bottom of the screen, under "Related Settings", there is a URL for "Date, Time & Regional formatting" which leads to the "Region" page, at the bottom of which there is "Additional date, time & regional settings" which leads to a different screen where I can change the time zone. So I select my correct time zone, save and for the next 10 minutes or so, my time zone is correct. But then the software automatically reverts back to the incorrect time zone.

Does anyone know how to set the correct time one so the change sticks and is not automatically modified to something that is WRONG?