[Gary R.]

Greetings and welcome to the forum!

Breakers sometime buzz when current is flowing thru them. I would turn them all off, then on and off, one at a time, to see if you can find the culprit. If none do, then try turning one on, then the next and so on. It may be the master breaker causing the buzz as well.

Another possibility might be loose wiring at the rear of the panel.

Just a few ideas, I know another member more learned than myself will offer help soon.

Take care!