Confusing message

I tried to change my email on my store and got this warning:

“This will affect 2 stores. If you’d like to change your email address for a single store, learn how to transfer ownership.”

To my knowledge (and intent) I only have one store. I don’t know what this means.

Plus it wouldn’t let me change it, but more concerned about having a store I don’t know about. When I log in I get only one choice of store, how do I verify there is only one.

Interestingly it required my new email to log in, so it appears changing the email was accomplished. It didn’t even give me a list to choose from this time (even though before I had to choose from a list of one). So I guess I’m good.