Just in case someone is as stupid as me just press [Esc] on your keyboard to enter the configuration menu. here you can

- Set the pixel scaling (2x,3x,4x)
- activate the "crt-mask" (filter that tries to emulate a crt-look)
- choose between original aspect ratio in a frame (Artwork) and in the original spect ratio with back borders (stretch)
- Input configuration (I had to you the reset entry afterwards for the changes to work)
- Save/Load one of three save states