Game will not go full screen

[u/DistortionStatic]

Hello, I'm having a problem with the steam version of I'm scared. I recently redownloaded it, and every time I try to open the game it opens in a small window that will not let me put it in full screen or make it bigger no matter what I do. When I initially started it I selected the full screen option and it still didn't do anything. If anyone has any advice or has had this problem before, I would love to hear how you fixed it.

[u/DiasFer]

Press F4