change (one's) mind
1. To change one's original opinion, choice, or plan. Politicians get criticized for flip-flopping, but I think we should value the ability to change one's mind on an issue. I guess he changed his mind and decided to go to the beach instead.
2. To persuade or cause one to change one's original opinion, choice, or plan. I never liked mushrooms before, but you really changed my mind with this dish. He's set on buying that car. Don't bother trying to change his mind.