How to change the name of a group mms in iOS 8.1.2?

I have a group of friends and we made a group mms to keep track of things. There are more than 8 people in this group so I get nonstop messages from everybody and I would like to be more organized and make a name for it. I looked up how to and I did as it said: "Go to the details page and scroll downward and a 'Subject' area should appear and that is where you change the name". This was added back when iOS 8 just came out, I'm wondering if it has changed since then or maybe it's a hardware problem?