Can't login to Itunes with new AppleID/password
I can't login to iTunes Store.
I changed my AppleID and password a few days ago (due to possible email hack). Now iTunes Store will not accept either my old or new AppleID/password.
I can login to iCloud on iMac with new AppleID/password, can see Files on iCloud drive on iPhone, and it did do the automatic iCloud backup from iPhone last night.
I am using an old Mac OS (for a reason):
iMac OS X Yosemite 10.10.5
iTunes 12.7.4.76
iPhone SE iOS 12.0.1 (and I just noticed there's a 12.1 available).
iMac, OS X Yosemite (10.10.5), iTunes 12.7.4.76