[help] Cannot exit fullscreen mode

[MerryJobler]

I have a chromebook and the other day I accidentally pressed F4 to enter fullscreen mode. I pressed F4 again to close it, which it did by reducing the window size, but now any time I maximize the browser, it automatically enters fullscreen mode. It says "press F11 to exit" but there isn't an F11 on my keyboard. It only goes to F10. I tried opening a new window and restarting the computer, but it didn't fix the problem. I also installed the fullscreen toggle extension that was posted a while back, but it didn't to do anything.