sing a different tune
US /sɪŋ ə ˈdɪf.rənt tuːn/
UK /sɪŋ ə ˈdɪf.rənt tuːn/

1.
異なる意見を言う, 態度を変える
to change one's opinion or attitude, especially to one that is more agreeable or favorable, often due to a change in circumstances
:
•
After he lost his job, he started to sing a different tune about the importance of saving money.
仕事を失ってから、彼はお金を貯めることの重要性について異なる意見を言うようになった。
•
The company was arrogant, but after losing a major client, they quickly started to sing a different tune.
その会社は傲慢だったが、主要な顧客を失ってからすぐに態度を変えた。