(If instead you are getting distorted audio when recording your computer's system audio then please see this article: http://feedback.screencast-o-matic.com/knowledgebase/articles/713634)
To fix low and distorted microphone voice recording on Windows 10:
1. Right click on the Sound icon on your bottom right.
2. Click on Recording devices
3. Right click on the microphone.
4. Click on the Properties
5. Click on Enhancements tab
6. Check the 'Disable' box inside the box.
7. Click 'Ok'
If you don't see an Enhancements tab then look for a "Signal Enhancements" section in the "Advanced" tab and uncheck that box then it should work.