A complete newbie here. I've an addon domain i.e swimming.com . The primary domain is ie. history.com. When I clicked on the "View Site Information" next to my domain at the url, then the arrow button next to "Connection is secure", then another arrow button next to "Certificate is valid", I found out that the common name (CN) of swimming.com appears as "swimming.com.history.com". I really don't want the addon domain to have anything to do with primary domain.
Is there a way for me change the CN to become *swimming.com . What do I have to do?
Sent a ticket to my webhost already, maybe I wasn't articulating my concerns properly, I was told this is normal and my site have no loading problems. The wordpress site is on cpanel. – Thank you.

WordPress can only have one domain name assigned to it. Why do you have more than one domain name?
You can’t have 2 tld’s on a cert. You can have *.swimming.com for any subdomain that’s about it, a wildcard cert.
Your host probably adds your addon domain (say `example2.com`) to your account in the form of `example2.com.example1.com` (or `example2.example1.com`), and adds a CNAME and redirect for `example2.com.example1.com` to `example2.com`. That’s why the automatic SSL is assigned this way. To change this you will need to manually add your certificates and figure out a way to automate certificate renewal, or choose a host who doesn’t have this approach, or use a VPS that you setup as per your requirements.