March 4, 2015
To give you the best viewing experience possible on your computer, YouTube adjusts the quality of your video stream from standard definition (such as 240p or 360p) to high definition (720p or 1080p), based on the speed of your Internet connection (bandwidth). This is why you may notice that the quality of your video changes as you watch videos.
Change the video quality by going to the gear icon in the corner of the video player while on Youtube, and selecting your preferred quality. On mobile devices, adjust quality settings by touching the menu icon, then the gear. This option isn’t available on all devices (e.g. TV/game consoles), or connections (e.g. iOS on a mobile network).