How to use Future Cruise Deposit?

[M5M]

We have $100 in our account under Future Cruise Deposit.  Can that be used as on board credit or is it only for the actual deposit? I'm confused by the wording online........ This is what the website says: 

 

"Any available Future Cruise Deposits can be applied to your next Holland America Line booking. Cruise Credits and Cruise Deposits can be combined. The onboard credit amount displayed is based on the length of your cruise vacation and type of stateroom or suite."

 

AND, can I apply it myself to my online account? Or do I need to stay on hold for hours to talk to a live person? 

[Cruise Suzy]

FCDs are for deposits only. However, some FCDs come with OBC attached. That OBC can only be used on the cruise that the FCD is used for.

 

I use a TA and just tell her to use my FCD as the deposit. If there is any OBC attached to the FCD, it is applied automatically and shows on my confirmation.