Thank you for your continued efforts.
Closed Firefox, cleared it cache, cleared everything cached by Java.
That did not work.
I opened the "About thread" and pinned it and that change is now persistent.
So it was not pinned and that function appears to be there to allow an individual to un-pin stickies in a forum.
Recall that I pointed out above that my pinning the "About" was not working at that time. So there may a bug that one cannot properly pin a post of one's choosing that is not site-pinned.
I did not get to try logging out then back in because I could not find where that functionality is hidden.