Favicons

This is for the website http://www.kennedyac.com.
I installed yesterday the plugin All In One Favicon. I loaded the new favicon (a red “K”) in the correct file formats to the Frontend and Backend locations. Despite cleaning cache, the Genesis favicon still appears in some browsers.

The current Frontend favicon results:
Chrome–Genesis favicon
IE–Genesis favicon
FF–“K”, which is what I want

The current Backend favicon results:
Chrome–“K”, which is what I want
IE–“K”, which is what I want
FF–“K”, which is what I want

Whatever guidance you can provide me would be appreciated. I WANT TO LEARN HOW TO DO THIS and it has been driving me nuts trying to discover the solution on my own.