I've seen various solutions to this problem with Roku blaming individual channels and someone claiming it's a universal issue. None of that is true in my situation. I have a TCL 49S405 Roku TV. The volume issue changes from the Roku Channel to Hulu to Netflix, etc. I have 3 other non Roku TVs in the house on the same WIFI system and none of them have this problem. I can watch the same program on Hulu on my Vizio TV (using a Roku box /Express) as my wife is watching on the TCL and she has the volume issues and I do not. The problem is ONLY with the TCL Roku TV. There are no volume leveling settings available on these problem channels. It seems to be locked out/unavailable when I press the * button while viewing the program. It annoys my wife to the point that she wants us to throw the TCL away and buy another Vizio. I'm not going to point fingers, but there are so many complaints about this issue, that you would think Roku would want to address it with the TCL manufacturer. The problem ONLY occurs with my TCL Roku tv and not with any of my other TVs using a separate Roku device.
The sound problem is not from the content providers, Roku can put in sound limiters, or set standard audio levels to their content providers. The sound level jump is extremely annoying and just makes me leave the Roku channel. If I leave the channel, I cannot possibly watch the commercials for products that are paying to reach viewers like me. It seems like other users have complained but with no responses or excuses.