How do I change the canonical name alias so I can transfer my domain name to Comcast?

I just switched to Comcast from Verizon.  I registered my own .com website a few years ago but Verizon took it over.  Now that I'm with Comcast, I need to transfer my domain name to Comcast.  I've put in a request to do that.  But now, Comcast's automated system is asking me to "Change the canonical name alias."  I'm not a tech guy so I stumbled around and got onto my verizon account and found the Manage my DNS app.  That's where I ran into a dead-end.  I have no idea how to chane the source alias or the target value.  

Verizon has an option of associating a domain name with a website but it only lets me choose verizon websites.  I go into the advanced functions and I'm totally lost.  There's no helpful label that says "Source Alias" or "Target Value."  Any help on what to do next would be greatly appreciated.  Perhaps someone has had to go through this process themselves?  Thanks in advance!