change one's tune
To make a change in your story, statement, or claim; change your way of acting.
Изменить отношение к чему-либо; поменять мнение или образ действий.
The man said he was innocent, but when they found the stolen money in his pocket he changed his tune.
Bob was rude to his teacher, but she threatened to tell the principal and he changed his tune.
You are going to fail if you don’t change your tune.
Ты потерпишь неудачу, если не изменишь своего отношения к ситуации (или поведение).