1
general::
Make important decisions, exercise authority, as in Nancy said that it's her turn to call the tune. The full term is Who pays the piper calls the tune, meaning whoever bears the cost of an enterprise should have authority over it. [Late 1800s] Also see the synonym CALL THE SHOTS.
American Heritage Idioms
2
general::
Phrase(s): call the tune
Go to call the shots and call the tune
McGrawhill's American Idioms And Phrasal Verbs