Change active display screen

I am trying to make a script that changes the active display screen.
I got a setup with 3 screens and can only have 2 active screens at the same time, so I want to automate the process by making a script for it.

Screen 1(Main) and 2(Extended) are my main screens.
I also got a third screen that I use for watching movies and such.

I've tried searching both the forum and google for relevant problems, but I can't seem to find anything.
Also tried looking for the display settings in the registry, but gave up searching without any idea what to look for.
Do you guys got any tips?

Regards,
Akarillon