Apple TV Upgrade

If you have an iPhone you can use that to move over most of the informaiton. However, please remember the Apple 4 & 4K (I'd recommend getting the 4K model) you will need to load the apps you want. Apple TV 3's do not have an app store to load apps, they are hard wired. With a new Apple TV it does have an app store so you will be able to have all the programing you did plus much more if you want it.

You will really enjoy the new TV OS and the speed of the device. I just upgraded my last Apple TV 3 to a Apple TV 4K over the weekend and couldn't be more happy. We have 3 Apple TV 4Ks in our home.

The 3rd gen didn't run apps, those were preset 'channels' that used basic web templates and were sent to the system via server. The HD and 4K also run a completely different system, TVOS.

When you setup the 4K it would work more like an iPhone, where it has preset apps from Apple and the rest are downloaded from the store. They do employ the 'one home screen' feature so that you can keep those in sync between multiple ATV's or for those who have upgraded between HD and 4K.

You buy the Apple TV 4 or 4K. There is no formal upgrade program.

No, there is not. If you had another 4K unit there would be. However you are worrying about something that will take you about 30 minutes. It's a really minor thing.