With AT&T it's easy, not matter which phone you have. Go to a Device Support Center (ask at your local AT&T store if you don't know where the nearest one is - it's in the back of the store, and might be in your local store and you never noticed it) and ask them if they could please update your phone, since you never got an update notice and there's no update choice in About Device. (If they have an update for the M8, which they probably do, they will.) The only problem is going in when you're 9th on line. Bring some reading material and be prepared to stand for a while.