I personally think they should have a better system in place than this staggered rollout. how they do it now feels sloppy with little reason
Has anyone here with a 2016 Premiere+....Gotten the OS 9 update yet?
As far as the above mention of advanced options for audio, have you tried hitting the * key while watching something like a Netflix show? they pop up for me there, and I think they are in the regular settings under audio too. One thing you could additionally try is disconnecting power from the Roku with the issue for about 30 seconds then reconnecting to see if it just needs a power cycle.