I have a pair of 32"monitors. I wanted DOSBox to open on the second one, but it wasn't happening. I had DOSBox starting up in full screen mode. I finally figured out that my primary monitor is 4K. My secondary is 1080p. So I just switched the Wiindoze configuration to using the 1080p one as primary and it all works fine now. It opens full screen on the monitor that I wanted it to open on. The desktop icons are on the wrong monitor, but that's not a big deal.

I created this account just to share that tidbit (4k and 1080p), but when I clicked on the verification link the page that I'd been viewing disappeared. Sorry about that

Steve