Hi James,
I do not see this happen in Ambari 1.7.
If I log into Ambari using admin from 2 machines, then I can edit & save configurations.
If I go to Hosts > choose a host > Configs – Then I see the no-entry sign you are speaking of – which is expected.
Can you let me know if your colleague is logging in as Admin and is following the same way as you to get to the configurations?
Have you tried using a non-cached browser session?
Thanks
Dave