I look EVERYWHERE but can't find anything called Account Menu. Where does everyone else find it? It's not on the top of the screen. It's not in System Settings. Apple.com is no help at all. Can anyone advise me please?

I need to play a song next week when I present a Zoom meeting, but the music that is on my iPhone and MacBook Pro refuses to sync to my new iMac. A popup note says I need to authorize it in my Account Menu. Account Menu isn't on top of screen, nor in System Settings, nor anywhere else I can fine, and posting this question in the Apple.com support site gives me no help at all. I realize it's probably really simple, once you know where it is, but that's the problem—I don't know where it is.

I will be extremely thankful to anyone who is kind enough to spell it out to me.