My AutoSSL certificate doesn't show the primary domain as the common name. Can I change the common name of my certificate?
You cannot directly adjust the common name on your certificate, however, you do have some options to adjust what is shown.
If you must keep your addon domain in the same cPanel account, and you aren't using the particular domain listed as the Common Name, you can exclude the domain from AutoSSL.
Otherwise, you could split the addon domain to a separate account using WHM's Convert Addon Domain to Account feature.
WHM > Transfers > Convert Addon Domain to Account