In the Options dialog, Applications panel, you may see some legacy "Adobe" settings at the top of the list, but "Portable Document Format (PDF)" is the key one now. You can type or paste pdf in the search box above the list to filter it.

"Preview in Firefox" uses a built-in PDF renderer. It is not as fully featured as Adobe's, so you may find a few cases where the page is blank, but I would expect most PDFs to appear reasonably close to Adobe Reader fidelity.

Open in Adobe Reader should download and launch the PDF externally. This is in contrast to Adobe Acrobat (in Firefox) which would use the Adobe plugin (I do not see that on your plugin list).

Your application prefers are stored in a settings file named mimeTypes.rdf. Occasionally this file can become corrupted with double entries that cause it to misbehave. The usual medicine is to remove the file and have Firefox rebuild it and then make the PDF change again. Here's how:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Show Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > "power" button
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, then rename mimeTypes.rdf to mimeTypes.old. (I suggest renaming rather than deleting in case you need to restore it or review its contents later.)

Start Firefox back up again, and choose your preferred PDF viewer in Options.

Does the change stick?

If it still gets lost, please consider:

• How to fix preferences that won't save
• Utility programs like Advanced SystemCare and others with "browser protection" or "home page protection" features may roll back your settings changes between Firefox sessions.

I followed the instructions and I was hoping that this would work, but unfortunately it did not.

The selected option (Nitro pdf reader plug in) will still not stick and any other option results in a blank screen for any pdf document.

Steve

In that case, could you investigate:

• Our support article "How to fix preferences that won't save "

• Whether a security/utility program like Advanced SystemCare or others with "browser protection" or "home page protection" features may be rolling back your settings changes between Firefox sessions

OK. I just wanted to let you know that a Refresh fixed the prpoblem.

Steve