SOLUTION:

For some reason I had ";" showing before the words system.externalscreen.
By removing these I was able to get it on a secondary screen.

Prefered external screen retrieved from ssh : xrandr

system.externalscreen.prefered=HDMI2

Force selected external screen to resolution ex : 1920x1080

system.externalscreen.forceresolution=1920x1080

Thanks a bunch!