Feral Heart

hello, i started up feralheart and i wanted to try out fullscreen when i started play, my whole screen turned black and it said i had to change settings to 600x or something i tried everything to get it off fullscreen but i cant, so i currently cant play feralheart...when i start it up it says the same and i need to spam alt+f4 to get it off sometimes i just need to restart my pc. i dont wanna reinstall feralheart because itll take a lot to put all the mods and stuff back, and im sure i forgot half of what i got..

please help ;-;

i also dont wanna get late for the halloween party ;_;