It could be the work of one of your add-ons, or even add / mal-ware. Look thru your add-ons list and make sure you know what each one is and what it does. Also, check the programs that are on your computer

Windows: Start > Control Panel > Uninstall Programs. Mac: Open the "Applications" folder Linux:

• Ubuntu Unity {web link}
• Xfce: Applications Menu category sections
• options depends on the package manager and the desktop environment

Go thru the list. If you find something that you don't know what it is, use a web search.

Troubleshoot Firefox Issues Caused By Malware {web link}

Try just resetting Firefox. Refresh Firefox - reset add-ons and settings

https://support.mozilla.org/en-US/forums/support-forum-contributors/710576 Possible Mal-Ware Scan For Macs

Download the Mozilla Search Reset {web link} This add-on is very simple: on installation, it backs up and then resets your search preferences and home page to their default values, and then uninstalls itself. This affects the search bar, URL bar searches, and the home page.

The reset button did it! Thank you so much

Try delete browser cookies and extensions.