ITs not a multiple-monitor related question.
I have a 3440 * 1440 monitor. Accidently the right side of the panel is broken. So I was trying to project the screen to the left side in 2550 * 1440 resolution. But when scale it as aspect ratio and change the resolution, the projection remains in the center I was trying to move it to the left side of the monitor to make the monitor usable for a couple of days. Broken monitor Change TO 2k