Using different Apple ID for media & purchases on Mac OSX Ventura

For historical reasons, I have a different Apple ID for media & purchases to that I use for iCloud logon on all my devices. I had to logout of my Apple ID and re-login to fix up an issue with Family Sharing being connected to wrong Apple ID. Now that I have logged back in to my primary Apple ID, I cannot see how to change the Apple ID account for Media & Purchases to the other account - it has just defaulted to the primary login Apple ID. You used to be able to tell it to use a different Apple ID account for Media & Purchases (which I have set up on my iPhone and iPad) but I can't see how to do this now. Oddly enough, once I re-setup Family Sharing, I could tell that to share purchases from the secondary Apple ID account.