My Client size is stuck on 1024 x 576

I already tried looking through the settings in League to see if I could change the client size and the only option is 1024 x 576. The client size changed suddenly one day and I don't know what I did to change it. I've already tried to use the keys CTRL and + or - but that didn't work either.

If someone could respond as soon as possible it would be great. It's bugging me a lot.

I'm using a macOS High Sierra.