Config mic after initial setup?

[laguerita]

I accessed Duolingo from one computer, did a lesson or two, then went home. Different machine. How can I rerun to mic config to be sure my voice will be properly recorded in DuoLingo?

I'm using Chrome in Ubuntu, and just plugged in an aaaaancient (yet functional) USB webcam. I want to run the config to be sure DuoLingo will get the audio via that webcam.