Settings-Panel is closing when i try to change a setting. This means i can't change movement mode but settings like keypress intervall are stored.

That's odd, I can't replicate that on my systems. Can you tell me more about your setup, was it the PC version and which screenresolution?

Indeed it has something to do with 21:9 resolution, don't ask me why... in windowed 2560x1080 this happens too, not in 1920x1080 (fullscreen / windowed)

Edit:

Yes, PC-Version. This also happens at 2560x1440