Social shares redirect to a broken link. How can I change that?

Social media buttons in a sent email direct people to "link.potomacco.com."  I didn't set up a CNAME to that subdomain; I set up one to links.potomacco.com.  Where do I change the social media button options to make sure they point users to the right location?  See screenshot; this is what happened after I clicked on the Facebook share icon in an email I sent to myself.  Thanks!