I'm running BiaB 2019 in a two monitor environment with Win7 64-bit. Not as fancy as yours. Wish I could afford two 4k TVs, but what I do have is -- to my left, my primary, which is running off my video card's digital connector -- what's it called, I forget? And in front of me is my secondary, which runs from an HDMI output. My primary is an older 22" screen that isn't quite 1080p -- it's 1680 x 1050. My secondary is an LG Ultrawide -- 2560 x 1080.

When I boot my computer the CMOS splash screen appears on my primary -- the monitor to my left, which I actually use as my secondary, and when Windows boots it also appears on this screen.

OK, these are the "system settings," I'd guess you call them. But on the Windows Control Panel's Display Settings page, I have my LG Ultrawide set as my #1 monitor, and my old AOC 22" as my #2 monitor. What this does is, for example, when I install a new piece of software, all the installation popups occur on my LG and the new shortcut is also located on my LG's real estate, if you will.

When I first setup this LG Ultrawide, everything appeared stretched out because of its extra width. But I was able to toggle a setting which reformatted everything such that the proportions were normal and I just wound up with about twice as much real estate.

Now, when I run BiaB -- and any other program, far as that goes -- if I have it set to run on the LG, then that's where it runs. Always. And any sort of popups associated with the program also open up on my LG. All programs behave in this fashion. In fact, when I've dragged something to appear on my left facing screen, it stays there until or if I move it back. IOW, when I shut down that software and reboot it, it will appear where it was last, on the left-facing screen. But when popups occur with one of those packages -- yep, they show up on my LG.

Since I'm having zero problems, I'm wondering now if it might actually be a Windows problem, which concerns me, since I've yet to upgrade to Win10.