If the names of sound devices assigned in Windows are repeated, then when selecting a sound device from the game's option screen with the same name as the currently selected device, you will be unable to Confirm it.
To fix this, open the Sound Control Panel and check that there aren't multiple devices registered with the same name.
Even if the sound devices have been confirmed and they have different names, Windows still might register them with the same name. In the following example, there are 2 devices registered as "speakers":
When selecting the BB Voice Output, in general when the device is changed, “Confirm” can be selected:
However, when a sound device with the same name (“Speakers” in this example) is selected, the “Confirm” button isn’t displayed. This is because two or more audio devices with the same name are registered:
This issue can be addressed by changing the device name. From the Sound Control Panel, select one of the devices with the name repeated, and open “Properties”:
Change the name of the device in the Properties window. In this example, the name is being changed to “HD Audio”:
Once the name has been confirmed to be changed, confirm in the BB Voice Output from the game’s sound options that the device’s name has been changed. If that is the case, then any device should be available and the Confirm button will appear: