PDF Editing Issues

How to Make Fillable PDF Form Fields Unchangeable After Signing on iPad

Algirdas Jasaitis Oct 18, 2026 868 views

Question details

The user needs to flatten a fillable PDF form after adding a signature on an iPad so that the form fields become permanently locked and unchangeable.

How to Make Fillable PDF Forms Unchangeable After Signing on iPad

Product: Adobe Acrobat Reader Mobile
Device & OS: iPadOS
Scenario: Signing a fillable PDF form on an iPad and attempting to save it in a read-only or flattened state.
Observed behavior: The free version of the Adobe Acrobat Reader mobile app does not provide a feature to directly flatten form fields, leaving the document editable after saving.

Before you start

Ensure you have saved a backup copy of your original, editable PDF form, as flattening a document permanently locks all fields and prevents any future edits to the entered data.

Solution 1Recommended

Use the iOS Print-to-PDF Feature to Flatten the Document

Since the free Acrobat app lacks a flattening tool, you can use the built-in iOS 'Print' workaround to generate a flat, uneditable copy of your signed PDF.

The iOS operating system includes a native method for converting documents into flattened PDFs using the Share menu's Print function. By 'printing' the document digitally, iOS merges the interactive form fields and signatures into the background of the page.

Open the signed document

Open the Files app or your PDF reader on your iPad and locate the PDF form you have already filled and signed.

Access the Share menu

Tap the 'Share' icon (a square with an upward-pointing arrow) located at the top or bottom of your screen.

Select the Print option

Scroll down the Share sheet menu and tap on 'Print'. This will open the iOS Print Options screen.

Generate the flattened PDF

On the print preview image displayed at the bottom, use two fingers to pinch outward (zoom in). This action automatically converts the preview into a new, flattened PDF file.

Save the new file

Tap the 'Share' icon again in the top right corner of the new preview, select 'Save to Files', and choose a destination to store your unchangeable PDF.

Verification: Open the newly saved PDF in any reader app and tap on the previously fillable fields. They should now act as standard text and cannot be edited.

Solution 2

Use an Online PDF Flattening Tool

If the native iOS print method is inconvenient, you can use a secure web-based PDF tool through your iPad's browser to lock your form fields.

Comprehensive PDF Editor

Use WPS Office to Fill, Sign, and Secure PDFs

WPS Office provides a robust PDF toolkit for iPad users. You can easily fill out forms, insert digital signatures, and export your files securely to prevent unwanted modifications.

1. Install the app: Download and open WPS Office from the App Store on your iPad.
2. Open your form: Import your fillable PDF form into WPS Office from your device storage.
3. Fill and sign: Use the integrated PDF toolkit to type into the form fields and apply your digital signature.
4. Export as flat: Save and export the document using the provided sharing features to ensure the final copy sent to others cannot be easily altered.

Seamlessly view, fill, and sign PDF forms directly on your iPadHighly compatible with Adobe PDF and Microsoft Word, Excel, and PowerPoint formatsLightweight, fast, and features a familiar, user-friendly interfaceExport capabilities that help ensure document integrity and security

microsoft office alternative - wps office

Frequently Asked Questions

What does it mean to flatten a PDF?

Flattening a PDF means merging all separate layers of the document—such as fillable form fields, annotations, and digital signatures—into a single, static background image. This prevents anyone from clicking into the fields to change the information.

Can I edit a PDF after it has been flattened?

No, once a PDF is completely flattened, you cannot easily edit the form fields or remove signatures, as they become part of the page's base image. It is highly recommended to keep a blank or unflattened backup copy if you anticipate needing to make changes later.

Why doesn't the free Adobe Acrobat app lock my signed forms?

The free mobile version of Adobe Acrobat Reader is primarily a viewing and basic markup tool. Advanced features like document flattening, permissions security, and form field locking are typically reserved for paid subscriptions like Adobe Acrobat Pro.

PDF Troubleshooting