Sub Domain on Premium Site Won't Stop Pointing to Main Domain

I’m in Wix Studio.

I have a domain (call it FIT).

I have a site for FIT that is published under FIT’s domain.

I created a separate site for EDU-FIT.

I have created the subdomain EDU-FIT.

When I add the subdomain EDU-FIT, it’s pointing to and replacing FIT.

I can’t figure out how to get EDU-FITto NOT point to FIT.

If I’m understanding wha I’ve read, you can have one or more subdomains under a domain if the domain is Premium.

FIT is premium. So I should be able to set EDU-FIT under FIT. Correct?

I see EDUFIT in the DNS FILE, but what values do I change pointing.wix.whatever to, if this is what I’m supposed to do?

How do I get EDUFIT to point to the EDU-FIT site I made for it and NOT point to FIT? The site for FIT is different than EDU-FIT. Or am I doing this wrong? Do they both need to be in one site?

I’ve also tried purchasing a domain for EDUFIT and it says its not available.

Many thanks,
Jami