To move a game to another monitor, set your preferred monitor as the primary display in Windows display settings before launching the game, or use the keyboard shortcut Windows Key + Shift + Left/Right Arrow to switch the game window between monitors if it's in windowed or windowed borderless mode.
I have a triple monitor set up; If I'm playing a game on my main monitor and my monitors go into sleep mode while the game is running (Paused to go to the restroom on wed/revenge of taco Tuesday) when it wakes up the game often moves to another monitor. I usually run my non VR single monitor games in borderless Windowed Mode so the Win + Shift + arrow keys work for me.