How do I change the callsign / registration in career mode?

In Career mode. I am always being called VH-GMZ which I dont like. How do I change this?

I would think you go to the EFB, Flight Details and set the Registration and/or Flight Number, then re-file the flight plan with ATC.

I haven’t tried it though.

Registration there is empty

Found it.
Have to go to Free Flight, select an airplane then go to configure and the Aircraft Identification Tab

Was driving me crazy