Dual monitors How to KEEP FULL SCREEN on 1

I have a dual monitor setup I am a noob to openSUSE, what I want to know is how I can I watch something FULL screen and work in the other screen without it minimizing in the other?

When I watch a movie or something in chrome/firefox I can full screen it on one monitor until I click somewhere on the other screen then it minimizes. How can I make it so the other screen stays FULL?