over one’s head

over (one's) head

1. Too complicated to be understood by one. My jokes always seem to go over Stephanie's head, so I'm glad you think I'm funny at least. A lot of this technical stuff is way over my head.
2. Bypassing one's authority. She just wouldn't listen to me, so I had to go over her head to her boss and complain about it.
3. Lingering as a source of concern or worry for one. All these bills are hanging over my head, and I don't get paid for another week. I'm so glad that exam is over—it's been over my head for months.
See also: head, over
Farlex Dictionary of Idioms.

over one’s head

mod. confusing; too difficult to understand. This stuff is too hard. It’s over my head.
See also: head, over
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • (something) is over (one's) head
  • be on the ball
  • (it's) good to hear your voice
  • be out of (one's) head
  • be at a disadvantage
  • at a disadvantage
  • address comments or remarks to
  • address (one's) comments to (someone or something)
  • address (one's) remarks to (someone or something)
  • be in it for