How can I enable or disable the built-in PDF viewer in Mozilla Firefox?

@june.crooks 

To enable or disable the built-in PDF viewer in Mozilla Firefox, follow these steps:

1. Open Mozilla Firefox and click on the three horizontal lines in the top-right corner to access the menu.
2. From the dropdown menu, select "Options" (or "Preferences" on macOS).
3. In the Options/Preferences tab, click on "General" in the left sidebar.
4. Scroll down to the "Applications" section.
5. In the search bar within the Applications section, type "PDF". This will filter the list and display the options related to PDF handling.
6. Locate "Portable Document Format (PDF)" in the list and click on it to select it.
7. On the right-hand side, you will see a dropdown menu labeled "Action". Click on it and select the desired action:

• To enable the built-in PDF viewer, select "Preview in Firefox" or "Use Firefox".
• To disable the built-in PDF viewer, choose "Always ask" or "Use other..." and select another PDF viewer installed on your computer.

Note: If you choose "Use other..." and select an external PDF viewer, Firefox will prompt you to download the file instead of opening it in the browser.

1. Close the Options/Preferences tab.

After following these steps, the built-in PDF viewer in Mozilla Firefox will be enabled or disabled depending on the option you selected.