Hi @cmirajkar,
When a quiz is created, it can either be created as a Classic Quiz or a New Quiz, but it can't really be both. It's possible to migrate quizzes from being a Classic Quiz over to a New Quiz. It sounds like you're working with banks, which does add a slight wrinkle in migration from Classic to New Quizzes at this time though. In order to migrate a question back to a New Quiz item bank, you'd have to have the item bank used in a classic quiz, then migrate that quiz to a New Quiz. Banks which aren't currently associated with a quiz can't be migrated to New Quizzes. If you're trying to go the other direction (new quizzes back to classic), I don't think there is an official process for that.
Hope this helps!
-Chris
