Hi Neet - you may have sussed this already but....
I had this problem too.. I ended up calling them and saying "look... I am not technologically stupid, but I can NOT find how to do this!"
Sign into mygov, Click on Centrelink (you must have it linked as a service?) then there is a button that looks like 3 lines (a 'menu' button) likely in the top left, depending on what device you're on. Then go down to Personal Details, and it's in there.
APPARENTLY they couldn't put it under 'Claims' or anything you know.. OBVIOUS... because it is not a government benefit, it's your money.
Pfft...