How do you transfer a child custody order between states, California to Ohio?

In 2007, My daughters father signed an agreement allowing my daughter and I to move to ohio. She primarily resides with me in Ohio with most vacations going to him in CA. he is now giving me a difficult time about returning her to me. How do I make her a permanent resident of Ohio, or transfer the custody stipulation to ohio. Do I need to file for custody in ohio?