Can you be more specific about your issue? If the content you are streaming is not in 4K then you are not going to get that quality. Just because it's a 4K TV doesn't automatically mean that everything you stream will be in that resolution. On Roku players there is a display setting to set to the resolution of your TV but I don't believe Roku TV's have this because it will automatically be set to the highest quality the TV is capable of, and I assume that is 4K HDR @60hz. Without more information the best advice to give is make sure the content you are streaming is a 4K video.