Use model in place to create a (small) geometry surface on the monitor, and put a decal image on this surface. (Not sure for the monitor, but for the TV's you can't put it directly on the face of the TV model because it will have two material faces in one another).
You can set the decal luminance to "LCD screen" for a good representation of an actual LCD screen.
I see you have multiple monitors. Create the geometry surface in the family, not in place