How do you replace a leaking tub spigot that sticks throughn the wall?

How do you replace a leaking tub spigot that sticks throughn the wall?
There are two types of tub spouts. One is a metal one that threads on,(see image) and the other is a chrome over plastic "slip fit" spout,(see image). Which one do you have? Back to you, Tom

Tom, do you have a pic of the slip fit so the poster can see the set screw?

Tom, do you have a pic of the slip fit so the poster can see the set screw?
The set screw is located under the square hole under the spout in the rear. Regards, Tom,