When you’re using multiple microphones simultaneously, or there’s an interference, the mic will not be connected or work. So you can change to other available channels.
Try following the video below to change frequencies and reset the whole system, and take a quick look at the spec. (Change frequency: from 1:20 to 1:37 and reset the whole system: from 1:52 to 2:42).
Change frequency:
Click on the channel button of the transmitter. The figures on the LCD will change.
When the light on the receiver flashes green for a second and turns red, it has changed successfully.
Reset the system:
Make sure you’ve changed the fresh batteries and other frequencies.
Turn off both transmitters and the receiver.
Turn the transmitter on and press the channel button 10 times in a row. Then the 564.00 appears in the flashing screen.
Turn on the receiver when the screen is flashing. The light will turn green, flash red in a second, and turn green again.
Click the mic channel to confirm when the receiver is on green light.
The Transmitter screen stops flashing. The indicator of the receiver turns from green to red. Now it’s reset.