Magewell USB Fusion HDMI & USB Video Capture Device - Manual (Page 102)

Setting WEB CAMERA Audio
In the AUDIO area, you can select an audio device as the WEB CAMERA audio,
that is, the audio that switches along with the WEB CAMERA video.
The audio input from the WEB CAMERA port can be used as a global
microphone (which is used throughout a presentation and does not
switch in/out with any scene) or WEB CAMERA audio. When you select
the audio input as the global microphone, you can no longer select it as
a global microphone .
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