Quirky AppleID Problems

I have always been able to log into my current AppleID account for use in iTunes, iBook, Apps. However, a few months ago, something started logging me out of my account, and I get a generic message telling me there is no server available, other times it says there is a security or admin problem. Yet I'm able to buy music in iTunes, which I assumed was processed through my AppleID, or account info, from AppleID.

Now, I find myself unable to purchase a new, customized Mini M1 because the obviously mismatching info I need to complete the purchase cannot be accessed because of an unknown problem Try again later. Later, later, later.

I know there's an AppleID free support line (but don't have it), and could order the machine at Apple Store, but jeeez. They will either give me my fifth AppleID, or this mess will get even worse.]