Thanks for the input, Moultipass.
I tried the resizing thing, and it did not work with BIAB.
Then I tried changing the monitor priority, and it did move. Apparently BIAB only wants to open on monitor 1. It's an unusual quirk, but it seems to be the case. I had forgotten that when I originally set up my monitors, I screwed up the order of them in the system. But it all seems to be ok at this point. I have some layout work to re-arrange now, but at least things are kind of where I wanted them in the first place.
Anyway, that quirk might be something to fix in BIAB.