How to Change the Microphone
To change the microphone settings, navigate to the Settings tab and click on 'Preferences'. Next, click on 'Devices'. You'll find microphone options for both when a headset is plugged in and when a normal speaker is being used. Click on the respective dropdown labeled 'Microphone' to view and select the different available options for each scenario.
In Call
While in a call, click on the Settings button to open the 'Sounds' dialog. Select a microphone from the appropriate 'Microphone' dropdown, depending on whether you want to change the microphone for the headset or for the speaker.