Can you refresh a monitors screen?


I’am working at a schoolproject and everything is going as it’s supposed to go.
But I have a problem and it’s probably a very stupid question, but here I go.

I have an Options Menu where you can choose and set your games resolution.
but if you go from let’s say 1920x1080 to 800x600.

There will be blackborder at the sides. Now I have no problem with those bars BUT
they still show “images” from the previous resolution?

Now how can I fix that and how did this happen?
I searched everywhere but I did not really find something that could help me :slight_smile:

(hope my english is good enough)
I suggest watching this tutorial from the Unity learn site.