If you get the build from patreon, on the select screen, press UP, and select the arrows to change stages
Okay, I got it to work. I've tried selecting the arrows on the level select before to no avail, and me getting kinda angry and trying everything I even messed with the controls and that seemed to do it. I don't know if it's just me but if I have the default controls on I can only press enter on the level selection screen, no up, down, left or right.
Thanks for the quick replies anyway!