hello desunny, vulnerable plugins get blocked regardless of the particular version of firefox you're on at that time. if the regular consumer installer by adobe doesn't work, please try it with the full offline installer instead that can be obtained at https://www.adobe.com/products/flashplayer/distribution3.html (use the windows exe-installer for plugin based browsers)

Thank you Phillip. That worked. I still don't understand why the Add-On Manager upgrade doesn't resolve the issue. Mozilla should just provide the link that you gave me, along with the instructions you gave me. Problem wouldn't have existed! (Sorry...I know I'm being a brat...I've just gotten tired of struggling with this issue.)

I sincerely offer my thanks for your help.

it is just difficult sometimes, as within the last week or so; keeping up with the Flash Player security problems and their patches.

• See https://helpx.adobe.com/security.html#flashplayer
  Note bulletins are issued and often have one or more updates later.

Where Adobe offer special links offering the latest updates in advance of changing their standard pages we try to let people know on this forum. Wthin a few days the updates should be available to those with Adobe Flashplayer set to auto update.

As soon as the standard pages have the update available Mozilla update Firefox's blocklist so that users of outdated FlashPlayer receive a warning and a link to Adob'es page for the check and upgrade.

Before December 9 Mozilla had not updated the Blocklist https://addons.mozilla.org/firefox/blocked/ for Flash since Mar 2013. Mozilla really only adds stuff to list when it is of serious concern with security, stability or malware.