The pad life indicator thingy doesn't physically do anything. Its just there to tell you how much brakes are left. Once you take off your rear arm and don't remember where the pointer went, the pointer becomes basically worthless. I don't judge my brake wear by the pointer, I just take off my wheel and physically look.
You may have to adjust the arm forward or backwards on the splines on the hub. Don't worry too much if it doesn't look like the old one.