My OS is Windows 10 Home Premium, 64-bit. I have refreshed Firefox and have installed the latest version. I have repeatedly verified that my default Browser (Firefox) is registered in my OS settings for "defaults." But when I open Firefox, it frequently says that Firefox is NOT my default browser...and I go to "options" to fill the box, again and again re-designating Firefox as my default browser - even though my OS settings already shows Firefox as my default browser. This is frustrating, to say the least! Help. Please. :-(