Why is it when the tool is alligned in z and is rotated around the z axis (like if the tool put a srew in a table) only RX and RY change? Why is it not only the RZ?
Not sure what you mean exactly. I just tested this out on my simulator and only RZ values changed. Maybe you’re looking at some values referenced to something other than Base?
You should be able to replicate it, @eric.feldmann. 
If you align Z+ of the tool with Z- of the Base frame, which is probably what’s happening for s215595.
As I mentioned, you most likely have your Tool Z+ pointing in the Z- of the Base frame. If you point Z+ upwards (truly aligned with Base Z), then you will get a rotation only in RZ.
You can also read more about the rotation vectors used in the robot here: Universal Robots - Explanation on robot orientation