We have 2 accts on our iMac (running 10.14.6; haven't updated to Catalina yet) one for us and one for our kid. Separate log in credentials. Kid has set up his own iTunes acct and so has his own Apple ID. We are not signed in to his acct on our side. I have confirmed we are signed in to our own Apple acct.
I want to update software but the Apple ID username that appears in the App Store is our kid's Apple ID and there is no way to change it.
Any ideas on how to make the App Store reflect the correct username/Apple ID?