When you're setting up the Backup Device Switch, you can do it individually for each virtual audio channel. But if you find a setting you really like and want to stick with for a while, we suggest going with the Link All Output Channels option for simplicity. This way, your chosen backup device switch and its order will be applied to all virtual audio channels, which saves you time and hassle!
When setting up Backup Device Switch please remember that only the active devices are shown. If you have anything that is currently not plugged in but still want to set up options for, please make sure to use switch 'only active devices' dropdown to 'all devices'.