Does a notarized agreement over ride a court order in indiana?

me and my ex husband made a agreement and then had it notarized. now however he is behind on his child support therefore he isn't supposed to claim and its actually my year to claim anyways. so what i want to know is since i made this agreement with him and notarized it, do i have to go by that agreement or can i back out of it since our divorce judge never approved and signed the agreement?