Allowing users to return to partially completed form.

How do I allow users to return to a partially completed form in order to complete the details?

I understand that you want to enable your users to save the form and fill it later. This can be achieved by enabling the option Auto-fill from the Form Preferences.

Please refer to the guide below for more information on Auto-Fill feature.

https://www.jotform.com/help/227-How-to-Enable-Auto-Fill-Feature 

Please note that this feature saves the data into the local browser storage of the user so it's required to continue using the same computer and browser. If you need form users to continue later using another device and browser, you may use the Session method explained in the guide below :

https://www.jotform.com/features/save-and-continue/?

Hope this information helps!