The output settings for the card are configurable in the Desktop Video Setup Utility. They are in the Video Output settings tab, in particular the During Capture radio button.
The Desktop Video Setup Utility including the various Video Output settings are described starting on page 15 of the Desktop Video manual:
https://documents.blackmagicdesign.com/ ... 8098810000Be aware, however, that any software that is using the DeckLink SDK to access the card can also override these settings that are configured via the Setup Utility. Software like Blackmagic's own Media Express will honor these output settings from the utility, but it is possible that other software may not. It just depends on how the software is using the card.