How to make it so that when you press play (F8) on the imac keyboard, itunes does not open?

Question

macOS

Good afternoon.
Tell me please.
How can I make it so that when I press play (F8) on the imac keyboard, it opens not itunes, but the application I need?
Didn't fully formulate the question. I'm clarifying =)
It is necessary that when you click on f8, it does not open itunes, but, for example, a dizer.
And if the dither is already open, then clicking on f8 would turn on the music, and f7 f9 would also work accordingly.

Answer 1

https://www.wikihow.com/Set-a-Keyboard-Shortcut-to...

Answer 2

fn+F8
fn is the lowest left key. It also works on all top keys, which doubles the possibilities. you can also check the box in the keyboard settings so that fn is automatically pressed on all upper keys.