Thank you for your quick reply! I didn‘t realize the button in the top left let you change the outline individually. That works, no problem at all. Good advice! I played around with it and the problem seems to be, that if I set the outline for the individual parts separately (with the button in the top left) some of them (in my case wings, eyes, nose, mouth) won’t change at all if I try to do it with the button for all parts afterwards. With all the other parts it works just fine.
It’s a very minor thing, but the parts that don’t want to change in that regard are always the same, so it seems like a bug.
Another question that I have is the color picker. If I’m in one of the color tabs I can’t pick a color from the palette (by clicking) and if I try to use the color picker the window zooms in and the palette is off the screen. Maybe I overlooked another button, but that makes it hard to get the right color from the palette. I could use of course the color picker from macOS, but I guess that wasn’t your idea.