Protect PDF after Certified Signature

Is there a way to prevent a PDF document's content from being altered after it is signed with a digital signature pad?

Steps I have successfully taken so far:

1. Used DC Pro's "Prepare Form" tool to add 3 input fields to my document: Sign, Date, and ID#.

2. Used document level JavaScript to populate the Date field with System Date, and ID# field with the document's file name (excluding the file extension).

3. Used DC Pro's "Certificates" tool to define a signature field, with Topaz Sig Pad as the default input.

4. Closed the PDF document and reopened it with Reader DC as the default program. The Date and ID# fields were automatically populated as desired and I signed the Signature field with the Topaz pen.

5. Closed the document.

The problem I'm having now is that even through Reader DC I can subsequently alter the Date and ID# fields and save those changes in the same document.

I see that Preferences in DC Pro contain encryption and password options (which I can't use for my purposes) but I cannot see any security options to prevent document changes after a certificate signature is added - is there a way to make that possible?

Alan Grant