Prevent clicking the submit button until all fields are filled out

Under the Dim's within your Submit Questions Button sub you can paste something like below. Check that it includes all your questions as i'm only assuming which ones are the questions based on my understanding of your code.

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You can also put a public variable at the top of the module:
Public AnswerCount As Long
In each Ans_Click sub, when the answer is entered, increment the AnswerCount by 1.
Then in the Submit button code, check the number against the total number of questions. If less then pop up a message.