I think this is a good opportunity to learn some electrical basics.
To test a switch, you need to set your MM to continuity test.
You sort of need 3 hands to do this, but you connect the black and red prongs to the prongs of the switch. When you engage the switch, there should be continuity (beep if your MM is audible)
https://www.youtube.com/watch?v=lB-aULIjiog
Your post is not clear. Are the windows moving at all when you press the switch?
If the motor is not spinning correctly, that can increase the amperage and blow the fuse.
So, it might be the motors, as well.