Toasty__

Whenever I attempt to launch RL craft using MultiMC, i get this phenomenon where the display for the screen is in the bottom left corner. https://imgur.com/l6DFbkj BUT, the controls are bound to where they'd usually be in fullscreen, and when I close my computer I can see it flash. If anyone has any solutions, that'd be great. I've tried the twitch launcher, but that doesn't work. I've tried technic, but it crashes. I'm on a Mac, so if that's the problem, then I'm kinda fucked. Thanks!