Thanks for trying our soft. See below for answers:
"How can I just record sounds from computer only, not sounds from microphone. I don't want the noises in the house get recorded."
In VAS(Virtual Audio Streaming) main window, switch to 'real microphone input' panel, then click the 'stop' button to stop recording microphone voice.
"When I muted microphone on my laptop, your program also stopped recording sounds from computer."
Microphone should not impact the recording from computer. Set VAS as your default sound card, then click the 'record' command in VAS systray menu to start recording sounds from computer.
http://www.virtualaudiostreaming.net/support.html