How to change self shadowing settings on character?

This is my very first question on the forum, and I’m quite new to UE4.
What you can see on the picture is head of my character with a bit of hair (actor with static mesh) attached to it. Both share the same material but the top bit clearly stands out.
I’d like to change the self shadowing on my character to the one used by static mesh.

284742-hair.png