Version 3.5.8
Device Manager
The device manaager window allows you to define which devices (cameras, mics, etc) are loaded by Wirecast on launch.
In the above image, the iSight has been disabled.
If the checkbox is ticked, then the device will be loaded, otherwise it will not be loaded.
This is a global action - it affects all documents loaded by Wirecast.
With some devices, you might unchecked all of the input channels except for one to allow Wirecast to load only that channel.