I realized that when you move a rigged character toward the sides of the scene the parts split up a bit.
I guess it´s depending on the Camera and that the angle from the camera gets a different angle but I hope there is a sollution to that.
Any one had the same problem and found a sollution?
Either, hold down the alt/option-key, then use the up- and down-arrows.
This will move the layer 0.001 forward or backward.
Hold down shift + alt/option. this will move the layer 0.01.
Or, use the Layer Properties Panel and type-in your desired value (z Axis).
I often move the objects in z-pos by selecting in the side view and use the left and right arrow to move them but maybe one click is a big jump and really not recommended?