Hello Kangalarue,

Are you referring to the Firefox PDF icon like in the first attached screenshot?

If so, right-click a PDF file, and click "Properties". At the "Opens with:" option, click "Change...", then when the "How do you want to open .pdf files from now on?" pop-up menu is shown, click "Firefox" . Finally, click "Apply". All PDF file icons on your computer should now be changed to be the same as the icon in the first screenshot.

Refer to the attached screenshots for additional context if needed.

Kindly mark this answer as the solution(solved) if it managed to help you!

I'm sorry to say that it is not the shortcut icon that has changed. I keep a number of pdf files on my desktop and it is the icons that represent these that have become so hideous. The icons for files that were already in folders have escaped and still have the Firefox on black background that all files that I open with Firefox used to have. It is this Firefox I want for all my closed files. Thank you! (I'm sorry I can't send you a screenshot: it doesn't seem possible to screenshot the desktop. If you can tell me how it is done, I will send you one.)

Hello Kangalarue,

Is this the Firefox PDF icon that you want? If so, just follow the previous steps I provided and if you have 2 installations of Mozilla Firefox like I do (The one with the black background is the Microsoft Store version while the one with the blue background is the version downloaded from Mozilla), just choose the one with the black background in the "How do you want to open .pdf files from now on?" pop-up menu. If not, just choose the available Firefox option.

Regarding on how to screenshot the desktop, you can use Window's built-in Snipping Tool by pressing the Windows key and typing "Snipping Tool". In the Snipping Tool program, you can click "New" and then choose the snipping mode that you want to take screenshots in. For desktop screenshots, the usual way is to choose Full-screen Snip when the program is open on the desktop. After taking screenshots, press CTRL + S to save the screenshot at your desired location.

Hopefully my answers managed to help you, and if they did, kindly mark this answer as the solution(solved)!

Hi Kangalarue, Have you tried opening any of the pdf files which were in folders? All of them changed to the PDF icon for me. If you look at the Applications section in your Settings, it seems Firefox changed the icon for PDF files (not MS). Shortcuts to web pdf files stayed the same.

Oh dear - I never thought Firefox would change icons from beautiful to ugly! I haven't dared open any files in folders in case they too became hideous. Please, please, please - how do I get the old icons back?

The Release Notes for Version 100 say: New users can now set Firefox as the default PDF handler when setting Firefox as their default browser.

Apparently, the PDF Reader in Firefox is now an Application with a distinct icon. You would need to make a Registry Edit in Windows to change the icon back.

Thank you! I am happy to edit registry - I've done it before - but I may need to come back to you to ask what the relevant registry item is called if it's not obvious.

It's pretty obvious in Registry Editor.

Hint: in the Data String - change the 5 to a 1

Thank you, but I've done it another way - with FileTypeMan.exe (free download from Nirsoft). It worked like magic. It even had the old Firefox icon in the list of icons to choose.

That's a Cool Tool! I was going to suggest it if you ran into any problems. Glad to hear that you're back to original.

Thank you! I meant to add to my previous post that I hadn't had an email about your reply - and now I am answering two replies! Yes, FileTypesMan.exe is mega-cool tool! Just got lucky finding it.