Any possible webpage comes each time ? if yes then it may be because of some bundled software that changes your homepage constantly . So prefer to scan with a any one of malware scanner : Malwarebytes Or Adw Cleaner . Some third-party toolbars and add-ons change Firefox's home page and search settings. You can quickly reset these with theSearch reset addon . Also having a possiblity of User.js file overriding preferences which configure firefox configuration files manually. Steps : Click on menu>click on help>Tap on Troubleshooting Information after that Under the Application Basics section, click on Show Folder. A window with your profile files will open. Now exit from firefox (menu> exit firefox).

• Open the file user.js with a text editor (like Notepad).

  * If there is no user.js file, these steps won't help you. 

• Remove the lines for the options you want to be able to change. You can delete all the lines if you want to be able to change everything.

Save the file and close the text editor. now do change as you have done previously.

There is software like Advanced SystemCare with its Surfing Protection feature that can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.

This lead to me possibly fixing it. I found the user.js file, also have Visual & opened it to find only 4 lines of code. Erased 1 that didnt seem important, funny thing was I opened FireFox after deleting the line & it showed back up. On the Troubleshooting page at the top was a ' Refresh FireFox... ' which I think may have safely removed all the dumb add-ons. Thank u 4 the help :-)

You can delete the user.js file.

If the content reappears then try to save a dummy user.js file with no content and set the property to read-only.