How do I turn the microphone back on?
I turned it off because it couldn't hear my responses. I like to turn it back on.
Where it shows you're profile name (In my case, Azwerth) and picture, you have to hover over that, and select Settings. The options are right there :)
Your answer put me on the right track, but it didn't work quite as you suggested. Hovering over my profile didn't produce "settings" (perhaps because I have a Mac). I clicked on "Edit Profile"; then clicked on "Account." At the bottom of the page, I clicked on "microphone--on." Thank you for your help! (Duolingo should make this kind of adjustment much easier and more obvious.)