Forum Settings Not "Sticky"

Day before last, and out of the blue, I started receiving email notifications about forum posts.  Not just my posts, but EVERYBODY'S posts.  I turned off email notifications long ago.  And now they are turned back on.  By somebody.  Not me.  I have tried to turn them off again in my forum settings.  But when I hit the "Save" button nothing appears to happen.  As in, nothing.  Like the "Save" button doesn't work.  And for sure if I log out of the forums and log back in, the notification check boxes are all checked again.  I figured maybe it was a browser scripting thing, so I used a different browser.  Same result (or non-result, so to speak).  I used both Google Chrome (with scripting enabled), and Microsoft Edge (default settings).

I also tried using the "computer" icon/image in upper left of forum pages (per a suggestion in somebody else's post on this same/simiar issue) and made sure I wasn't subscribed to "daily digests".  I wasn't.  And again this morning, more forum emails in my Inbox.

So, I need a fix.  I can write a junk mail rule, but what I would really like is for the forum settings to, you know, work.