- Access the display settings window by right-clicking an empty space on the desktop background. You can also type “change display settings” in the search bar and press enter.
- Click on the drop down window under Multiple displays and choose between Duplicate these displays, Extend these displays, Show only on 1, and Show only on 2. (Keyboard short-cut for display settings are Windows + P)
Windows + P
- PC screen only — Only the primary monitor is used.
- Duplicate — Secondary monitor shows duplicate desktop.
- Extend — Both monitors combine to offer an extended desktop.
- Second screen only — Only the secondary monitor is used.

- If you have more than two monitors, you have the option of duplicating two of them. The settings can be changed under Multiple displays. (i.e. show on 1 and 3, 1 and 2, or 2 and 3) This will allow you to mirror two of the three displays.
- You can rearrange the display windows by clicking and dragging them to control how the mouse will transition to the other displays.
https://www.windowscentral.com/how-connect-and-set-multiple-monitors-windows-10