YouTube will play 4K videos in 1080p
TV Serial # P502ui-B1
My TV will play amazon in 4K but will NOT play YouTube in 4K.
How do I get my tv to play YouTube in 4K?
The problem is that the hardware of your TV is not strong enough to process VP9, the proprietary video coding format developed by YouTube-owner Google specifically to handle Ultra HD video. On the contrary, 4K videos on Amazon are compressed via HEVC, not VP9.
To play YouTube videos in 4K or higher resolutions, a YouTube 4K converter may help you convert the formats or resolutions into something your TV can accept.