If you’re signed in, you’ll see your profile picture
for your Google Account in the top-right corner of the YouTube app or browser window. The info in this article is most relevant to users that are signed in. 
Home
When you open the YouTube Android app and sign in, you’ll land on the Home tab. Once you start watching videos, the Home tab will show you recommended videos based on your preferences and activity on YouTube. Learn more about managing your recommendations.
As you explore YouTube, you can always tap Home 
Explore
ExploreThe Explore tab helps you discover videos that are popular on YouTube right now. You can scroll through a list of trending videos or select a category, such as Music, to find videos just on that subject. Learn more about the Explore tab.
Subscriptions
SubscriptionsThe Subscriptions tab shows you the newest videos from the channels you’re subscribed to. A list of your subscribed channels can also be found at the top of the page. Tapping the channel artwork will take you to that channel. Learn more about subscribing to channels.
Notifications
NotificationsThe Notifications tab is where you can find your messages and notifications. Learn more about managing your notifications.
Library
LibraryThe Library tab is where you can find info like History, Your Videos, Purchases, Watch Later, and Playlists. Learn more about managing your Library.
Cast
If you have a Chromecast, Smart TV, or a supported streaming device, you can connect your YouTube app using the Cast 
Create
Tap Create 
Search
The Search feature helps you find the videos you want to watch on YouTube. To start, tap Search 
Profile Picture
Tap your profile picture 