Just in case you were getting comfortable with the YouTube app's latest design, it looks like there may be more changes in store. It seems a number of users are encountering a new YouTube interface, apparently triggered server-side without an app update.
The change sees YouTube's hamburger menu flipping right out of the interface, going the way of Google+ in discarding the left-side navigation drawer. Instead, users are given four primary tabs - Home, Trending, Subscriptions, and your profile. Interestingly, a couple of these tabs seem to have bars underneath to switch from, say, all videos to music on the home tab, or from uploads to channels on the subscription tab. Read More