Press the green flag and then... well, it's pretty self explanatory. ---Tuning mic levels--- Current levels should work if you lean in to your mic, but if not, hover your mouse near the top of the screen to tune your mic. Raise the value if talking is registered as yelling, and lower it if yelling is not registering.
Disclaimer: I do not condone any verbal abuse of Nano. I am in favor of keeping Nano happy. Go ahead and tell the 'recent user' displayed at the bottom of the screen not to be so mean to Nano.