Voice works...voice doesn't work....voice works

I was so happy last Friday that I found a way to make my voice work. But it did not last long.
When I logged out from second life, I found out that my voice did work because a test module was still open.:(
I know, I am not the smartest guy with pc, I learn every day.
I was looking through my settings in the configuration screen, and was trying some things out, when someone shouted:" hey Looker your voice sounds nice." I thought, how can that be, I did nothing, and was only in the test module of audio settings. I even did not change anything. Ok, I was happy at the time, so I pushed the button saying "Apply" and thought everything was alright.
Back to SL, I saw that it wasn't, I couldn't still not say anything with being heard on the grid.
Back to the settings of audio. Back in testing, and everything worked. Strange huh?
After some tries to push "Apply" and back to SL, I thought I had find it, as I did close the audio window, and my voice was still alive in SL. Great!! I even IM'd some friends saying that everything was fixed. But my enthusiasm was very low, when I later logged out. I saw that there was still a window open from testing audio.;(
Now I am back to the start, figuring out, how I can set that right without having this window open every time I want to say something in SL.
Not totally from the start though, as I already did say a few things, and I can have my voice heard on the grid.

UPDATE 08-20: This weekend I managed to find the correct setting for my voice to work on Second Life.
In my configuration settings there was a program "3D AUDIO". I have activated this setting and........I had a voice in Second Life!
UPDATE 08-22: I have voice alright, but not thanks to that "3D AUDIO", because after one day I even had no voice and sound anymore through my headset. I did turn that program off, reboot, and I still have Voice now. Sorry for those who thought to have found a solution, I still can not help you, as I don't know what changed in my settings.