What is the origin of the idiom "change one's tune" and when to use it?

The idiom "change one's tune" is believed to have originated in the 14th century. It is thought to have come from the practice of minstrels who would change the words of their songs to suit their audience. If a minstrel was performing for a king or other important person, they would sing songs that were flattering and respectful. However, if they were performing for a group of commoners, they would sing songs that were more lighthearted or even bawdy. This idiomatic expression is used to describe someone who has changed their opinion or stance on a particular issue.