The new YouTube UI features navigation tabs at the bottom, a move that should make them easy to reach on even the biggest phablets on the market. The tabs are also labeled so that you know exactly what they do, and the YouTube app will remember where you left off on each tab when switching between them.
Other changes being rolled out to the YouTube app include a separation of Account and Library to make it easier to find what you’re looking for. Your videos, including playlists and watch history, are in the Library section. Your Account and Settings are found in the profile icon at the top of the screen.
Finally, Google says that it has made the navigation tabs viewable on all pages except for Watch so that you can quickly jump between tabs no matter where you are.