How to prevent duplicate submissions?

how can i stop people filling out the form multiple times? I'm trying to avoid duplicate entry.

If you want to avoid duplicate entries you can add your form a "Short Text Entry" field and label it as Email or Cell Phone and set it as "Unique Question" from Settings. This configuration does not allow the users to fill out form multiple times. You can configure your form by following this guide: http://www.jotform.com/help/223-How-to-set-Form-Limits-Based-on-a-Unique-Question.

And if  you want your users to edit their submission, you can give them the edit link. Here is a guide how to do that: https://www.jotform.com/help/40-How-to-Let-Users-Update-Their-Form-Submissions-at-a-Later-Date.

If you don't like this solution there is another option: "Unique Submission" setting. Here is a guide that shows you the details of this settings: https://www.jotform.com/help/64-How-to-Set-Unique-Submissions-on-a-Form