To change one's behavior, usually in a better way, because you are forced to

You'd better change your attitude and behave like a decent person if you want to keep living here. My house, my rules!

Vedi di cambiare registro e comportarti da persona civile se vuoi continuare a vivere qui. In casa mia si seguono le mie regole!

The salesman was really mistreating a customer that was complaining a lot until he suddenly changed his tune when he realized that the owner was looking at him

Il commesso stava trattando in modo molto villano un cliente che reclamava, ma cambiò subito tono quando si accorse che il proprietario lo stava guardando

Joe used to brag about his illegal behavior, but when the police finally caught him and told him it was serious stuff, he started dancing to another tune

Joe ha sempre fatto il gradasso vantandosi delle sue "malefatte", ma ha cambiato musica dopo essere stato arrestato dalla polizia

The analogy is very old. John Gower wrote, c. 1394, "Now schalt thou singe an other song," and the literal phrase "change your tune" appears in a ballad about Robin Hood from about 1600. According to some scholars, it may refer to itinerant minstrels who would change the words of their songs to please their current audience