I recently had a custody battle with my ex. I won and he moved to another state. He is upset that he has to pay child support and wants to get a lawyer in his state. He wants to force me to let him sign over his rights. I live in Florida and he in pa. My question is is my custody agreement binding in his state and can he force me to let him sign over his rights?

He will have to pay child support no matter what he wants to do.
He can't force you to do anything.

Child support order is valid, no he can not sign over his rights, they are idle threats of someone mad.

Yeah let him waste his time and money trying then he will see it doesn't work that way.

Most states will not "Let" anyone sign rights away, unless there is something like a step parent adoption in the works. The states work together pretty well now on child support issues, and he will still have to pay no matter where he moves. But just remember, they work together on visitations too. Transporting children for visitation is rough and expensive. Usually both sides have to pay half for transportation, or drive half way, even if it is he that moved. Just something to be aware of.

Custody matters are the matter of the child's juridiction, not the parents... it only matters where the children have resided for the last 6 months.