Then using it even more wrong.
From the Cambridge Idiom dictionary 2nd edition:
To go over somebody’s head:
- to talk to or deal with someone’s boss without talking to them first
- if a piece of information goes over someone’s head, they do not understand it
You can use the expression in the following example: That tax declaration information went over my head.
In this example, the subject is not ignorant of the fact that (s)he’s being shown tax information. She or he doesn’t understand it.
It fits.