Naration

i have an issue with the narration ie voice speaking over live tv, to turn it off i go into audio and subtitle settings then i choose audio stream and change it to .....in my case English MP2 stereo and all is well no voice over, once i have done this i scroll down to set default for all channels and all should be ok, except it does not set for all channels, i have to do this every time for separate channels, even when i do change them and i switch the box off or reboot, i have to go through the same thing all over again, anyone having the same experience and is there a fix i've missed.