So in my current game, I'm playing as a count in southern greece. Atm I'm holding a viceroy title, which I assume I can't in any way change to a permanent title. This I understand, but what I don't understand is, why I can't create new duchies else. For example Athens will become a Viceroy title, but my provinces in Serbia won't. What decides whether a title that is made is made into viceroy title or into a regular duchy? Keep in my that in all cases here, I'm under the emperor of Byzantines.