Click on the "More options" button as highlighted in the image below. Click on the "Settings" button as highlighted in the image below. You are now looking at the settings menu. Note: Before setting up VoIP Accounts, I'm going to suggest some "essential" changes be made first. Without making the following suggested changes, your VoIP calls likely won't work properly.
Click on "Audio Options" and you will enter the Audio Options menu. Be sure to select your preferred Sound Devices for the Microphone input and Speaker output, as well as the Ringing device. When finished click on the "tick" to save any changes, you will return back to the settings menu. It is always recommended to use a headset with built-in microphone, for best results.
In my case, I selected the basic desk microphone that I had connected to my sound card. And, my USB stereo speakers for speaker output and ringing device.