I am trying to turn on Automatic Client Upgrade under Hierarchy Settings for the Sites, but when I access the tab, it is greyed out.

I tried this article for resolution: http://blog.coretech.dk/kea/automatic-client-upgrade-greyed-out/, but "All Security Scopes" is greyed out as well. The I account I am logging in with is designated as full administrator.

Any ideas?

You need to run it as the account that you used to install ConfigMgr.

Kent,

The individual that initially installed ConfigMgr has left this company. What is my option for getting Automatic Client Update turned on? Will it be as simple as running a site reset?