Video quality automatically changes to auto.

I put video quality to 2K, but few minutes later it changes to auto, becoming 720 or 540, or even 240 sometimes. My internet speed is high enough to play 2K video, my hardware and monitor also supports 2K. Even if not, it should keep to play the quality I choosed, with scraps if the speed goes down, but should not change to auto. Otherwise the ability to pick the quality doesn't make any sense if it always plays in auto quality. The weird thing is that when quality changes to auto, in "gear" menu it shows the actual quality that picked up automatically, but when I choose the quality from this menu, the check is next to 2K, not next to Auto, and I have to press it again to set 2K again. It's annoying to get distracted from video every few minutes (even less, during 10 minutes video quality changes at least 5-6 times), and it's unreadable in big monitor when quality goes down. Thank you! 😊