Can I limit the submission via question?

3. I have set the 'prevent cloning' function to prevent user can repeat take the quiz. But the alert message come out when I finish answer the question and wan to submit. Can I set the alert when detect the name is filled before?

Yes, this is possible. You can limit your submission based on a form question. Here's a guide:

https://www.jotform.com/help/223-How-to-set-Form-Limits-Based-on-a-Unique-Question

I hope this information helps.