change one's tune

To change one's attitude, opinion, manner, or stance on something, typically in a way that is more positive or agreeable. The mention of a hefty tip really changed the host's tune, so I think he'll be able to find us a table after all. After I threatened him with no allowance, my son changed his tune and started doing his chores.

Also, sing another or a different tune . Reverse one's views or behavior, switch sides, as in When she realized she was talking to the bank president, she quickly changed her tune, or I bet Dan will sing a different tune when he finds out what the salary is. A version of this term, sing another song, dates from about 1300, and it has been theorized that it alludes to itinerant minstrels who changed the words of their songs to please their current audience. The first locution was already in use by 1600. Also see dance to another tune.

To reverse one’s views, change one’s mind, switch sides in a controversy. The analogy is very old; John Gower wrote, ca. 1394, “Now schalt thou singe an other song,” and the actual phrase, “change your tune,” appears in a ballad about Robin Hood (one of the Child ballads) from about 1600. And a character in Samuel Beckett’s novel, The Unnameable (1953), says, “I have my faults, but changing my tune is not one of them.”