Currently the only way to do this is by having the arm artwork in the layers above the head. So if this is what you wanted, you'd probably want to find a way to swap the Body and Head groups, or have an extra group above the head that includes the arms. This video isn't doing exactly that, but it does show how to add extra groups to your character outside of the usual two (like hair in this case):
Thanks a lot! I will try moving the hand above the head and see what happens.