From the chatting list, tap the Menu Key > Settings.
Tap your account to access the following settings: Profile photo, Share your status, Notifications, Sound, Vibrate, Invites, Sound, Vibrate, Customize invites, Google+ profile, Phone number confirmed (Confirm phone number), Blocked people, Sign out, and Improve Hangouts.
Tap SMS to access the following settings: SMS Enabled (Disabled), Import SMS, Notifications, Sound, Vibrate, Group messaging, Delete old messages, Delivery reports, Auto retrieve MMS, and Roaming auto-retrieve.