Mac: System Preferences→Sound→Input/Output→Input Volume/Output Volume. Before the setup, turn down the volume control of speaker. b)Instead of speaker, please direct the microphone to your mouth for loud and clear sound. When plugging receiver in, do not place the mic directly in front of speaker. c)And keep the mic at least 9 feet away from speaker for perfect effect. Windows: Go to control panel→Sound setting→Recording Device→right click “USB PnP Device”→Properties→Levels. K037 K037 Signal Indicator(The indicator is green when paring with transmitter.It turns RED when paired successfully) 3.Turn the transmitter on and then receiver , when the light turns from green to RED , they paired successfully.The light stay on RED when it proper functioning. Same goes for output volume on “Playback Devices”. Someone viewed it: FIFINE K690 USB Mic with Four Polar Patterns, Gain Dials, A Live Monitoring Jack & A Mute Button $ 115.99 USD Liquid error: Could not find asset snippets/theme-controller.liquid During the use, a)slowly adjust the volume setting of speaker. Turn up the level of input and output to around 80% on computer.