Is looks like there was the ability to adjust the surround volume for rear wireless Roku speakers in version 9.4. My Roku TV currently has version 10 and my streambar pro soundbar is at version 10.5 all speakers have been updated today.
Devices: TCL Roku TV, streambar pro, wireless speakers, wireless subwoofer.
I had to start a show/movie that has 5.1 and press the * button on the remote, I was then able to adjust the surround sound level. I had to do this though the streambar pro, it does not work on my Roku TV which is pretty annoying. However my settings did seem to transfer over to the Roku TV as the surround is much louder. Very frustrating that I can’t make these changes in the TV. I have to go to the streambar, start a show and change it. I can’t even change it in the sound settings in the streambar pro! This is very inconvenient just to change sound levels of the surround, bass, or treble.
Update 2: My Roku TV FINALLY received the 10.5.4191 update and I am now able to change the surround settings through my Roku TV by pressing the * on the remote when using an app or live tv and adjusting the ‘sound settings’. Also some good news is that you can now add more Roku TV speakers to your existing setup for a total of 4 Roku speakers, streambar/pro, subwoofer.