Hello Rob,
You do need a load an organ in order to be able to assign it as a favourite. E.g. simply assign it next time that you load it for to play it. Once it's assigned as a favourite, you can use the list editor facilities (insert, delete, copy, paste, etc.) to move assignments around within the list if desired.
[I'll move this topic to the "Technical support" section of the forum once you've had a chance to read it.]