I have a weird multi-monitor setup at home. There are two 27-inch monitors on my desk, but I really don't need both of them for work, and usually my second monitor stays off all day. It doesn't even face the front of my desk: it's faced off to the side, in the direction of my bed, because I only turn it on to play games or watch TV from a comfortable horizontal. When I want to play a game on that screen, I set it as my primary display, Windows shifts the Start menu to that screen—and that's when everything gets a bit annoying.
Sometimes I forget to set my normal monitor back to primary, so the next morning I need to physically rotate the second screen so I can see it from my desk and restore the proper order. Or sometimes Windows gets confused, and saves the position of certain programs, like Slack or Spotify, on the wrong monitor. Every day I end up having to turn the damn thing on, let Windows pause a few times as it adjusts, rotate it around, move a window or two, and then put it back. Unsurprisingly, there's a way better solution.
Of course there's a Windows shortcut for this: Win+Shift+Left/Right arrow.
Normally pressing the Windows key + an arrow key will dock a window to the left or right side of your screen. Throwing shift into the mix, though, moves that entire window from one monitor to another without changing the size or relative placement. It's a shortcut I never really needed before this unusual multi-monitor setup, and didn't think to go looking for. But it's my new favorite.
When a program is hiding on the wrong monitor, I just click it on the taskbar, smack the shortcut and bam, it's back on the right screen.
If you've ever had Windows open up a program on a monitor that's not even turned on, don't let it boss you around. Just Win+Shift+Left and regain control.