Regarding the microphone related issue, please refer to the following link.
* How to record your voice in Windows Vista/7/8/10https://www.bandicam.com/faqs/how_to_re ... icrophone/
If it doesn't work, please let us know the model of your microphone.
Also, please attach screenshots of Bandicam Recording settings window and Windows Sound settings window.
We look forward to hearing from you.