Layers and Hierachies Question - I'm confused

I’ve been watching Adam Phillips’ Animate tutorials and I have hit a snag.

In this video, at around the 4:00 mark, he drags out 3 symbols: An upper arm, a forearm, and a hand. He then places the forearm on top of the upperarm, covering the rounded bottom edge of the upper arm.

That’s cool, but then at just before the 6:00 mark, he creates a hierarchy of the hand to the forearm, and the forearm to the upperarm… but the Upper Arms bottom rounded edge is still underneath the forearm’s drawing! You can see in the layer panel that the Upper arm is indeed on top, yet the forearm art appears on top in the camera view!

I really need to know how he does this, because there are hierarchies I would like to create where the top layer is not necessarily what I want on top visually. Please help!

There should be some tutorials on this on the Toon Boom video tutorials from the Toon Boom website - what you need to do is select the drawing with your Transform Tool, then with the focus (red outline) around the camera view, click on Alt+Down arrow to move it forward, Alt+Up arrow to move it back.