black bars around screen

The black bars appear when I start a game and tab out of it and they stay until I close them then the whole desktop looks like this

Hello, I am currently back home for the summer and im using my laptop hooked up to my dads 27 inch screen. The problem is I usually play on 24 inch and that is what ive grown used to, I really hate 27 inch monitors. Anyway can i have black bars appear on the sides of my screen in order to make...

Image of what I'm seeing here: View: https://imgur.com/a/b9ygHzC Just today, I noticed a black bar on all three of my monitors. It's about 1/8" wide and goes along the left, top, and right. I have changed nothing in my display settings; so I don't know what to look for. How do I get rid of...