Hello @Suchodolski, Katie ,
Welcome to Azure !
The right place to look out for the subscription owners is in the "Subscriptions->IAM->RoleAssignments->Look for Owner Role"
Refer below screen shot:
Above process is the recommended way !
Previously we used have something like Classic Deployments model which is going to retire now (next couple of months). The classic Admistrators tab is needed only if you are using Azure Classic deployments .
If you use that tab (Classic Adminstrators tab) - You will see something like Service Administrator (Who is the original owner).
If you see Co-Administrator (He is the second owner added by original owner)
Example Screen shot below:
Hope that clarifies your queries !