By default Firefox only allows you to preview PDF files in its browser.If you want to be able to work in or complete a fillable pdf form, you can by editing Firefox’s options.Instructions for doing so follow:
With Firefox open:
- Click the Open menu button in the top right corner and select options
- Under General scroll (if necessary) to the Applications section. Scroll down until you find the Portable Document Format (PDF).
- Under the action section the default is “Preview in Firefox”. We are going to change that by clicking the down arrow on the right side.
- Select the “Always ask” option. By choosing this option, you will be asked whether you want to open (allowing online form fill) or download the PDF file. The “Always ask” option protects you from other malicious PDF documents.
The new setting is automatically saved when you close the options tab in your browser.