Move questions between quizzes
After clicking to add a question to a quiz instead of clicking "A New Question" click "From question bank"
The new window will open with a list of all available questions in the question bank.
Simply click the checkbox next to each of the questions to be added to the quiz from the bank.
If you intend to move questions from a quiz to another quiz (and actually remove the questions from the original quiz then you'd need to do the following:
Check the question(s) you would like to Move and then select the quiz you would like to move them into from the dropdown list (See below).
Once finished making selections simply click on the Move To >> link and the questions will be moved from the source quiz to the destination quiz.