Sims 4 no longer in full screen?

Hi, I'm playing Sims 4 on my laptop and I've changed the graphics settings. I don't know what exactly I pressed, but suddenly I didn't have a real full screen mode anymore. It is definitely not in window mode, because there are black bars on the right and left and the image is now a square.

Can anyone help me with what I need to do to get me back to the correct full screen mode?

Did you change the display type? At the top left when you go to game options

No

Try to press button f11 when you are in Sims

Does not work too.

Usually you can change the resolution in the game options as normal. Simply change the display type to full screen and set the appropriate resolution.