Thank you, I have the same Issue.
The only (temporary) fix I found is to launch the game, then open the windows display settings, change your main monitor to the one you dont want to use, then change it back. The game SHOULD switch over to the correct monitor.
Let me know if it works for you.
First of all, though there are some issues I can see and feel a great game here. Here are some super important settings that should be in every single first person game:
Toggle ADS (For those weirdos out there)
FOV slider (Must be priority, I can't see shit rn, very disorienting)
Invert aim (For those OTHER weirdos out there)
Choose Display/Graphics card
Now on to personal issues. The game currently opens on the wrong display and nothing I do can change it (As there is no setting, see above). Other than that, it currently runs at a solid 20FPS on low settings, freezes when joining the pregame lobby (with a horrid view of a bunch of decapitated guys with open parachutes stapled to their open neck), and it also freezes for a solid 15 second EVERY time I jump out of the heli, which also seems to either randomly change the direction I'm looking or defaults it to the direction the heli was going. So jumping me 15 seconds forward in time and further disorienting me by changing the direction I'm facing, not a good was to start a game.
Other than those few, but VERY important issues, I've liked what I've seen. Health seems to be a bit high though, as I can headshot people without helmets 6-7 times before they get killed, though that might be server issues (Confirmed hits due to blood splatter). Then again, with the low FPS its hard for anyone to hit anything right now. I'll keep checking in to see if the display setting is added and if they fix the FPS, cheers.