How to track when the submitted data has been changed?

It would be helpful to be able to track the actual changes which were re-submitted 

Currently the only way to track changes made on submissions is with the email notifications as emails are re-sent by default each time a submission is edited. 

If you're using auto-responders then you should active this option, to do it go to the emails wizard, and open the email you want to edit: 

Once on the email wizard click on the advanced tab and turn on the option to send the email on edition: 

This way auto-responders will be sent again if the submission is edited. 

Thank you

so at this time there is no way to track the actual changes in the form?

No, unfortunately, there is no way to track changes made on your form submissions, the only way is the explained above with emails. 

If you want, we could escalate this thread to our second level support as a  feature request, but do note that this may take some time, but although we cannot provide an ETA we will ensure to let you know when / if this is implemented.