How do I manage my son who doesn't like having his clothes changed?

Age? . Your son's age is very important to know in order to respond to your question.
Don't go changing. Change him only when necessary. Frills and decorations can be irritating to some young children whose senses are still maturing (some makers have gone tagless.) when he needs to be changed, be firm but gentle, as when you are fastening the car seat straps. Limit how often you have this battle to only those times when you need to win it.