please also read this help article:
How to set the gain (Manual and Auto Gain).
You CAN set the gain when the microphone is in:
STANDBYE/IDLE mode (top LED is white)
BLUETOOTH mode (top LED is blue)
USB AUDIO mode (top LED is light blue/turquoise)
While RECORDING (top LED is red)
We don’t recommend to set the gain manually on the microphone using the +/- buttons while recording as the sound of clicking the buttons might be heard on the recording.
You CANNOT set the gain when the microphone is in:
External STORAGE mode (top LED is orange)
PLAYBACK mode (top LED is green) In this mode you can only set the headphone volume with the +/- buttons.