Just sharing this in case it helps anyone else. Something seems to have changed in Windows 10 / Windows Defender and the Controlled Folder Access feature.
SCII was not saving sound setting changes at all and it worked previously. I found lots of posts about 7.1 sound/etc but the issue is actually Windows Defender. Everything is updated, no issues elsewhere on machine.
I had to “Allow an app through controlled folder access” – and I had to find the specific SCII executable also (can’t just callout the launcher)
I have the Blizzard App on C drive. Game is installed on another disk. Perhaps this is why windows is tweaking out?
Anyways, added the file:
[disk volume]:\rest_of_path\Starcraft\Starcraft II\Versions\Base75025\SC2_x64.exe
to the exception list and now SCII working like normal.
related to this other post: