How to send only part Autoresponder email back to the user when the form is edited?

I also am looking for a way that once the submission is received, I could edit and then on second submission send only part of the form back to the applicant in an email. Can this be done? 

For example:

1) the applicant applies using part of the section of the form open to them and submits

2) On receipt of the email notification, I edit the form, adding the password to unlock the internal section of the form for internal use only

3) And finally when I submit the form the second time, a select part of the form is emailed back to the applicant.

Inside of this guide, you can find how to edit submissions:

How to Edit Submissions Made on Your Forms

if you want to send to your users only part of the form when the form is edited and via Autoresponder email, you will have to create one more Autoresponder email. You also need to set Send On Edit option to Yes inside of the Autoresponder email that should be sent when the submission is edited. 

You can also use conditional logic to send an email. 

How to Send Email Based on User's Answer

You can also check this guide if you want to create an approval workflow form:

A General Approach on Building an Approval Process Workflow

Hope this meet what you are looking for. 

Hi, if I edit the form and then want to send part of the form back to the applicant I have to set up a second Notification. Is it possible to poulate this from an email address that is added to the form?

Example. I ask for the email address of the applicant in the form, and once I have gone in and edited (checked that everything is in order) I resubmit the form and it automatically gets sent to the applicant (using the email address that they entered on the form). 

It should be possible, here are the basic steps:

1) Add an admin field and hide it. For example, a single choice field.

2) Add an email autoresponder.

You can edit the autoresponder template to add/remove some content.

The 'Send on Edit' option should be enabled for that email autoresponder.

3) Add a condition to send the autoresponder once the admin field is filled.

Note that the hidden field will be displayed to you in submission edit mode.

If you need any further assistance, please let us know.