Solved it! I just found an article about going into help, troubleshooting and opening my profile and the folder containing files. I deleted one of the extensions files as suggested (it actually said to delete 3, but only one was there), I restarted FF and was able to put on a persona. the article was in forums under personas not showing.

Previewing a persona only works on sites that are white-listed via an allow exception.

You can see the permissions for the domain in the current tab in:

• Tools > Page Info > Permissions > [X] Install Extensions or Themes
• Tools > Options > Security : "Warn me when sites try to install add-ons": Exceptions

Thanks cor-el. Does this mean when making changes in the future I go to tools>page info>permissions and check 'allow' temporarily to add a persona or theme or just if I want to preview with a mouse roll over? I use another computer at times and have the same settings, but can preview & try-on the persona without making any changes, so I'm confused on that. No big deal, just curious. In reference to that page info site, why was the Google Update added when I have add extensions blocked, and without warning me as my security setting is set to? Apparently there is no safe way to uninstall that add-on through any program of Google's or anywhere without affecting other settings, it can only be disabled.

That setting is stored as part of the Site Preferences.

Do not use Clear Recent History to clear the "Site Preferences"

• https://support.mozilla.com/kb/Clear+Recent+History

Clearing "Site Preferences" clears all exceptions for cookies, images, pop-up windows, software installation, and passwords.

Thought I hit post to this reply, so if you get it twice, sorry. Ah Ha! about clearing site prefs, as I was doing this along with clearing out my cache at times. Do I need to reset the pref (even if just temporarily when I want to add something), which ones and where? Life is a learning process, and thank goodness for people like you! I am trying to learn bout all this, as 11 years ago I knew nothing about computers (internet) as I lived in a very remote area where there was no access. Thanks again cor-el.