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HappyTeacher_63
HappyTeacher_63
Known Participant
August 21, 2026
Question

How can I lock or secure a PDF after using Fill & Sign so the signature can't be edited?

  • August 21, 2026
  • 1 reply
  • 4 views

Hello,

First, thank you for answering all of my questions as I work through Adobe Acrobat. I appreciate the support.

I am using Adobe Acrobat Pro 2026 (Enterprise). 

I’m trying to send a PDF for signature, but our organization does not use cloud‑based services, so we cannot use the E‑Signature (Request E‑Signatures) workflow. I would like to use Fill & Sign instead and then lock or secure the document so the signature cannot be removed or altered.

Is there a way to fully secure a PDF after using Fill & Sign so the signature becomes non‑editable?

I tried Microsoft Print to PDF, but the resulting file still allowed me to delete the signature when using Edit PDF. I also tried Save as Adobe PDF, but that did not secure the signature either.

Could someone please explain:

Whether Fill & Sign signatures can be made non‑editable

What Save a Certified Copy does

Whether “Certified Copy” involves saving the document to the cloud or if it remains local

Thank you again for your help.

    1 reply

    Amal Jaiswal
    Community Manager
    Amal JaiswalCommunity Manager
    Community Manager
    August 21, 2026

    ​Hi @HappyTeacher_63 ,

    Hope you are doing well, and thanks for the detailed write-up. That's really helpful.

    Quick question before the suggestions below: is this a document only you'll sign, or will other people need to sign after you, as part of an approval chain? Those changes determine which option fits best.

    To answer your three questions directly:

    1. Fill & Sign signatures do get flattened automatically once you save after placing them, so they're not "live" form fields anymore. But that's a different kind of lock than security. Flattened content can still be selected and deleted with the Edit PDF tool, since it treats it as an object on the page. That's why Print to PDF and Save as Adobe PDF didn't hold up for you; neither actually restricts editing, they just re-render the page.

    2. What you're describing, locking it down so it can't be altered, is what Acrobat's Certify feature does, not a "Certified Copy" save option exactly. It's under All tools > Use a Certificate > Certify (Visible signatures) or Certify (Invisible signatures). When you certify, you pick a "Permitted Actions After Certifying" setting, and choosing "No changes allowed" means any edit made afterward breaks the certification and shows up as invalid. That's the real protection here, since regular flattening doesn't stop someone from re-editing the page content.

    3. Certifying is entirely local. It uses a Digital ID, and you can create a self-signed one stored on your own machine. So the workflow would be: fill and sign the form with Fill & Sign as you're already doing, save it, then run it through Use a Certificate > Certify, choosing "No changes allowed" and a local Digital ID.

    Please go through the help articles that cover each part:

    - Fill and sign PDF forms: https://adobe.ly/4zt0AeJ 
    - Certify PDFs: https://adobe.ly/4cncdtR 
    - Create a self-signed digital ID: https://adobe.ly/45GJ2y4 

     

    Hope this information will help

    ~Amal

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