I am using a dual screen setup, with a BenQ 4k monitor and a HiSense 4k TV.
The upper screen (HiSense) is for the mixer.
The lower screen (BenQ) is for the main/arrangement window.
Some (not all) of my VSTis (in this case Serum) only open in the upper window and mostly outside of the screen. By that I mean that only the lowest part of the VSTi is visible and I can’t reach the top bar of the VSTi window to drag it down.
I would try dragging screen 2 to be under screen 1. Then I would do a round of moving any plug-ins that open half in one screen, half on the other, so that they are exclusively on one screen.
(Could it be that resetting window layouts from the “Window” menu in Cubase would do this easier? I need to test, but then again I don’t have this problem so that I will know if it worked.)
Anyway, once all plug-ins open in one screen or the other, but NOT half-and-half, between screens, it’s at that point that I would go to Windows’ screen settings and move the second screen back to its place on top.
I can’t remember if this works on plugin windows, but might be worth a try.
In Windows, pressing Alt + Space brings up this window menu in the top left corner:
Press M for “Move”. Now you can use the arrow keys on your keyboard to move the window around. After pressing one of the arrow keys, the window gets tacked to the mouse pointer and moves with the mouse position until you press a mouse button.