Making the iOS YouTube App Full Screen
Instead of viewing videos in a Web browser, YouTube users on iOS 7 have the option of watching videos in YouTube's standalone app. The app's interface will look familiar to anyone who uses YouTube on a PC, but there are slight differences to YouTube on a touch screen device, such as switching to full screen, that may not be apparent.
1 Watching Videos in Full Screen Mode
To get the YouTube app to play in full screen, first choose a video and go to its page. As it starts playing, tap on the video once. This makes visible several additional options, including dual arrows on the bottom right corner to toggle the image to full screen mode. Tap the arrows to switch the video to full screen; repeat the same process to reverse it. Note that switching between landscape and portrait mode while the video plays changes its display size. For example, widescreen videos will be larger in landscape mode than in portrait mode.