Hi wmschur, it sounds as though your data is intact, but not shared between two installations. Let's gather more information.

Some 64-bit Windows users are experiencing parallel installs: their Firefox used to be under the 32-bit path, but an installer or updater installs the new version under the 64-bit path. So that is the first thing I'd check, the location associated with your different desktop shortcuts.

Right-click the shortcut (if it's a pinned Taskbar button, right-click the button, then right-click Mozilla Firefox) and choose Properties. Windows should show the Shortcut tab with the Target field highlighted.

Are your different Firefox installations in different places?

Before removing anything: If you use Microsoft Office on your PC, change your default browser to IE or Edge. Otherwise, there can be a problem where Office is too stupid to figure out the location of your new default browser after the old one is removed.

Yes, I am 64-bit WIndows 10. On the task bar, I still have the old Firefox shortcut. On the desktop, I have the new Firefox shortcut. So two different shortcuts, in two different places. On the Start Page, from which I had tried to delete old Firefox, the new Firefox shortcut appears in two places. First, alphabetically, and second, under Recently Added.

I will set Edge as my default browser. It was only through Edge that I was able to reach the Firefox page.

Also, the failed installation coincided with an Adobe Reader failure. PDF could not be opened with Adobe Reader, and only opened with other programs. After I reinstalled Adobe Reader, I was able to get it to work as well.

Right-clicking the shortcut for New Firefox shows file location "C:\Program Files\Mozilla Firefox\firefox.exe." Right-clicking the tasbar button for Old Firefox shows a different location: "C:\Program Files (x86)\Mozilla Firefox\firefox.exe".

I have now set Edge as my default browser. Will await further guidance

Sound good. You probably can remove the older version under the 32-bit programs path --

C:\Program Files (x86)\Mozilla Firefox\

-- but first let's try to get Firefox 73 using your old profile.

Make sure the older Firefox is not running, then:

Profile Manager Page

In Firefox 73, type or paste about:profiles in the address bar and press Enter/Return to load it.

This page should list at least two profiles and could list more. (Each profile has two folders and one or more buttons. Do not use any Remove buttons!)

The profile that Firefox is currently using will have this:

This is the profile in use and it cannot be deleted.

If you know which is the old profile, you can click its Set as default profile button now. Then Firefox 73 should use it automatically at the next startup.

If you're not sure, you can examine the contents of another profile by clicking its Launch profile in new browser button. That will create a separate Firefox 73 process using the data from that profile. Once you're done checking, exit the window(s) associated with that profile as you usually would.

Can you get Firefox 73 using your old profile?

Trying noiw. Assume Firefox 73 is what I've been calling New Firefox.

I can see one profile identified by the name Profile: default. It is shown as not being the default profile.

The second profile is named Profile: default-release. It is shown as being the default profile.

Root and local directories are shown for each profile and button will allow me to Open Folder.

I do not know where to find a "Launch profile in new browser" button.

I must be looking for the "Launch profile" button in the wrong place.

I did find a Set as Default Browser for both profiles.

Found. I reread and saw that I had searched for the default profiles in the old Firefox.

Okay, I admit I'm confused. Is your new Firefox now using your old data and that part of the problem is solved?

Thanks, jscher2000 for your expert advice. I think I can now delete the 32-bit version of Firefox, but I am not quite sure how to do that.

Do I just delete the C:\Program Files (x86)\Mozilla Firefox\Mozilla Firefox and C:\Program Files (x86)\Mozilla Maintenance Folders? I get nervous about deleting folders not removed when I uninstall programs.

Hmm, in the Control Panel, do you have the two programs listed? That would increase the likelihood of successfully removing only the old one.

I think what I would suggest is, before running the uninstall for the old version, rename the folder of the new version to hide it and prevent accidental removal. For example:

C:\Program Files\Mozilla Firefox

=>

C:\Program Files\Mozilla Firefox New

If the uninstaller bombs and says it can't find the uninstaller, you dodged a bullet. If all goes well, you can rename the folder back and proceed with your life!

I had run the uninstall of the old version earlier. Then I installed Firefox 73. I ended up with two shortcuts - one on my Desktop and one on the taskbar. Clicking the taskbar shortcut opened Firefox with my bookmarks. Clicking the desktop shortcut opened Firefox with no bookmarks. Yet, they both may have opened Firefox 73, and it is possible that Firefox 73 is now located in two places. In Task Manager, only one Firefox program is listed. If I were to uninstall that, I think I would no longer have Firefox 73 working on my computer. But that's well beyond the scope of my knowledge. I think that if I leave well enough alone, I will have extra stuff in the x86 folder but I will be able to use Firefox 73 going forward.