The Program audio controls affect the volume of non-microphone sources such as PCs and the Blu-Ray player.
The Microphone controls affect the volume of the microphone(s) in the room
Matrix, or (normal) is the audio coming from the instructor PC in the room
The 1/8" mini jacks are located at student stations 1-4 and correspond to the laptop inputs at each station.
When the system is shut down, the audio source will automatically default back to the Matrix input.