A few weeks ago I had updated my 8100NEX to v1.5 and everything seemed to be working fine.

Today I used the navigation for the first time since the update and I noticed that the voice guidance was very loud and the street names were missing. The voice also says things like "Please leave highway now", which seems to be missing the article in that sentence.

So I poked around and tried first to find out how to reduce the volume of the voice guidance, without much success at first. Then, by chance I noticed a new (to me) button on the right of the volume popup, I says something like "auxiliary alerts" and setting this from the initial 8 to 4 reduced the voice guidance volume a bit. But it was still too loud so I tried reducing this setting even more, and finally to "0", just to see, but that had no additional effect.

Back from the trip I tried to poke around a bit more, and strangely, now that "auxiliary alert" button is gone so I can't even verify if I remembered the button label correctly. I have no idea what this setting actually does as everything else seems to be working normally.

So here is my question – has anybody here seen this button in the volume popup too and knows how to get it back, and what it actually does?

It is supposed to adjust the volume of the voice, and it's found when you press the volume buttons when in the maps.

it's better than the Volvo I drove a few months ago (rental), it said 'Please turn....'  I laughed the first time I heard it say Please!  

You can adjust the voice guidance volume from within the Nav app, it's under region I think (same place you choose the voices) plus there is only 1 voice that does the street names.  I lost a few voices on my unit when I did the update to 1.05, very annoying.