The company outlined the changes in a recent blog post:
Right away, you’ll notice we’ve added content categories across the top navigation bar to make it easy to for you to jump to your chosen section – whether it is TV, Kids, Latino, Search, or something else. Inside each category, you’ll discover what’s new in our content library so it’s easy to discover new shows and keep up with the shows you already love. You can also jump into your favorite shows right away with the “Shows You Watch” tray. We built this to make sure you never miss a new episode or lose your place in a series.
When redesigning the experience, we looked for ways to grant you instant access to exactly what you want to watch. Once you decide on the show you want to watch, simply press the “Play” button and the latest episode of the series will automatically start playing.
While your favorite episode or clip is playing, hold down the “Select” button until Subtitles and Audio appears to turn on captions.
You can get the latest Apple TV Software from the Settings menu or you can find the download links here.