RE: “marked as duplicate by Mari-Lou A, Edwin Ashworth, tchrist♦, FumbleFingers, RegDwigнt♦ Aug 15 '14 at 14:08 This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.” . How do I ask a new question, and what should it be about? . Crap. That’s two questions isn’t it?
In your new question, you should ask your new question (presumably with wording that distinguishes it from the prior question), and refer to the old question, and explain how it is not a duplicate. This will help the reader understand the nuances, and help prevent the from closing it as a duplicate.
It may turn out that the prior question in fact did cover what you're asking (but no answer supplied it). A new question would not be the right place for new or embellished answers to the the old question. That may be a reason for bumping the old question (many means for this), adding a comment requesting/emphasizing the additional nuance that you don't see in the given answers.