Buying your first Apple Watch is a delightfully simple experience for getting up and running. Buying your second Apple Watch to replace the first? It's a mess.
You know you've done everything right. You've let your Apple Watch and iPhone run all their latest updates. You've got your iCloud backups up to date. Why isn't your old Watch backup up to date? Why won't your new Watch find your old Watch backup to restore from? Expect to encounter multiple moments of confusion on the slow, awkward path to getting the job done that will make you scream "this doesn't feel like an Apple quality experience at all!"
After our own trial and error process, we've got the exact process you need to follow to get this done right. It's not easy, but it's the only way to get it done right.
1. Unpair your old Apple Watch
The process of unpairing your previous Apple Watch triggers a final backup of the watch, ensuring your new watch will be able to restore with all your fitness tracking and other watch settings up to the moment you retired your old model.
2. Setup your new Apple Watch as a new watch
At this stage, most users have their first "WTF is going on?" moment when they discover they can't find their old watch backup.
Didn't I just back it up? Why doesn't it appear as an option?
This is because your old watch is on the latest version OS because you've been keeping your devices up to date like you're supposed to, but your new Apple Watch just came out of its box and isn't up to date yet. Setting up as a new watch lets you do Step 3 so you can get to Step 5.
3. Update your new Apple Watch
Now it is authorised on your iPhone you can run the Apple Watch software update, catching it up to where your old watch backup needs it to be.
4. Unpair your new Apple Watch
Yep, now it's up to date you can ask it to leave so you can now pretend to meet it again for the first time.
5. Setup your new Apple Watch from your old Apple Watch backup
This is it. This is the moment. You will now be able to choose to restore from backup and you will be able to see your old watch in the list of options. This one will be slightly slower than the fresh setup, but we're finally there.
Moving on with your life, with your shiny new Apple Watch, can now proceed.
All up this process doesn't take all that long in added time, it's just a frustrating journey to go through. Ideally, Apple would let you point at your backup on that first run through and run a software update to prepare your watch to accept the correct restore target from the beginning.
But with the steps above, you'll be able to get the job done and get on with your day. Take a deep breathe, put the frustrations aside and move on with your day wearing that new Apple Watch just the way you wanted.