Are they not working at all? Are you getting any error messages when you try to use them?
Open the Galaxy Wearable app and scroll down and select Labs. In Labs you should have two options, one is a gesture to answer the phone and the other is to mute an alert, turn them on if they aren't already on. If you are talking about having the display come on when you bring your arm up to look at it the setting for that is in the Galaxy Wearable app under Advanced, just turn on the Wake-up gesture option.