1) Go to the MSN/Yahoo/Skype website and download and install the latest version
MSN: Tools > Audio Tuning Wizard, and follow the steps to set up audio
Yahoo: Download the Audio setup wizard from http://help.yahoo.com/l/us/yahoo/messenger/
Skype: Tools > Options > Audio setting , or go to https://support.skype.com/
Note: Make sure you select the correct device from the microphone list.
2) Select which microphone you want to use: webcam microphone, Multimedia Headset or laptop built-in microphone (soundcard)
3) You need to save your choice for the change to take effect