Help my Mic and speaker settings are not saving in Google+ Hangout!
Don’t worry, according to Google this is a known issue with them. The current alternative way is to save your mic and speaker settings in your Gmail account. So log into your Gmail account and go to the Chat settings page to save your settings. Until Google fixes this issue, this is the only way to save your mic and speaker settings for Google+ Hangout.
If your friends still can’t hear you, you might want to do some basic troubleshooting. E.g. if you have an external mic, make sure it is connected, and make sure your computer volume is turned on too.