physics constraint offset position

UE 4.26.1 Blueprint
I am trying to create an Actor blueprint with two cylinders just touching at the ends and a physics constraint at the touch point connecting them (Component Name 1 and Component Name 2). I want to modify the Constraint pos 1 and pos 2 to move them to the touch point on each cylinder, but whenever I modify the pos 1 and pos 2 positions, they immediately convert back to the original values. Does anyone know why this happens? Do I have a config parameter wrong, or am I missing something?
thank you