Try this first — the Audio Mixer. In a lesson, click the mixer icon in the top toolbar and raise the volume of whoever sounds quiet. It works straight away and needs nothing from them. It changes only what you hear, so it does not alter how they sound to anybody else, and in a group lesson each person adjusts their own.
If the mixer is not enough, the microphone input level on their computer is the next thing to raise — the steps below. To raise your own microphone level without leaving Muzie, open your audio and video settings, click Advanced options, and increase the audio input there.
The microphone input level is raised on the computer of the person who sounds quiet.
First Check the built in audio mixer & input controls.
Audio Mixer & Input Levels
Raise the microphone input level
In the computer's sound settings, under Input, raise the input volume for the microphone in use.
Reload Muzie afterwards.
Check the correct microphone is selected
Muzie uses the microphone chosen in Device Settings. In the lesson, open Device Settings, select the microphone in use, and click Save.
Check Muzie is receiving the microphone
On the screen where you choose your camera and microphone, a level bar sits under the microphone. Play or talk. If the bar does not move, Muzie is not receiving the microphone — see My Microphone Isn't Working.
Related
To make the other person louder for you: use the mixer next to the metronome at the top of the lesson. To raise your own microphone: Device settings (gear icon) → Advanced → mic input slider.