I'm probably not the first this happen just never find a solution!
There i have on my left a 24 inch screen connected by dvi middle screen a 50 inch screen set has main screen in windows and use hdmi connection right screen a old ibm 17 inch screen using dp to vga graphic card an nvidia geforce gtx 1060 windows 10 64 bits with uefi boot
So i launch some specific games like the sega megadrive and genesis classic on steam and the games start on my left , this also happen with a games named rack 2
After thinking is an id problem left :3 ,center:2 and right :1 I switch the screen position and put my 50 inch on the left side and the 24 on the center and the games is now booting on the 50 inch who is left screen
So there the problem , how i can say to the games to boot by default on the center screen then left screen