Set Extenal Microphone as default on Startup in Linux

steps.md

• Make sure PulseAudio is installed
• Search for "Startup applications" in applications (click on windows menu and search)
• click Add item
• In Command input - pactl set-default-source 'alsa_input.usb-0c76_USB_PnP_Audio_Device-00.mono-fallback' [refer below for how to get the name of the mic]
• Click save
• It should run automatically from next startup

How to get the name of the mic?

• LANG=C pactl list | grep -A2 'Source #' | grep 'Name: ' | cut -d" " -f2 stackoverflow
• This will list all input and output devices names. Copy the name of the device you want and pass to above patcl set-default-source command

Make a clickable icon on desktop, to set the source

• create a bash file with following text

  #! /bin/bash
  pactl set-default-source 'alsa_input.usb-0c76_USB_PnP_Audio_Device-00.mono-fallback'
  echo "done"
  

• save it as "setMic.sh"
• Make the file executable, with chmod or by right click on the file and going to properties
• Now we can double click on this file icon on desktop, anytime we want to set the mic as default source.