I am using my husband’s old iPhone. I want to change the Apple ID for iTunes to my account. How do I do that?
Go to settings then tap on store and you can sign out with his ID and then sign in with yours.
It is a little bit searching but i've changed it recently also. Go to preferences. Choose Store. Last one is Apple ID. Take this one. Log out. After that you can choose a new ID.
How do I change my Apple ID Name or personal information?
iTunes Store: Changing Account Information
How to change your Apple ID through your iTunes Store account