You have to reset your watch as new, and then reload from backup and then download the update. However, my series 3 watch updated, and has now been running into multiple problems that apple is quietly saying a few series 3 owners are running in to. It turns off randomly, and I have to turn it back on. The battery is draining twice as fast as normal. I lose all 'Sharing' friends and have to reload them. Throughout the day, all my stats (move, exercise, stand) will go to zero and start over. I'd be tempted to say to wait for the ios 7.1 update before loading, especially since practically every nice feature of the ios 7 is for series 4 and newer.