Pico8 doesn't let me choose emulator

Hello, I played some games both in .p8 format and .png as well, but for the latter I had to change from the default emulator/core (not sure what's the right way to call it) to be able to run games in that file format. I don't remember what emulator I changed to, I think it was fake08. After that, I could play both formats.

So, knowing that .png files worked, I downloaded a bunch to try them out (being aware that not every game will work because it's not native pico8) but now I can't even choose the emulator, for any game at all, not even the ones I could actually play before.

What did I do wrong or how can I solve this?