In Firefox, there is no straight way to lock the homepage. In addition, it is not as easy to lock your Firefox homepage, but a trick that you can try to lock homepage. To do this, you have administrative rights to your Windows PC. Instruction:
Open Notepad and type: pref (“browser.startup.homepage”, http://www.myhomepage.com;lockpref (“browser.startup.homepage”, http://www.myhomepage.com); Note: Replace myhomepage.com with the homepage URL of your choice.
Name the file ‘mozilla.cfg’ and save it. Now copy and paste this file to your Firefox folder at C: – program Files – Mozilla Firefox.
Now create another Notepad file and enter the following text: pref(“general.config.filename”, “Mozilla.cfg”); (Make sure you include the semi-colon). Name the file ‘local-settings.js’ and save it. Now, copy and paste this file at Mozilla Firefox – default – pref folder. Finally, restart Firefox and your home page should now be locked against changes. You can unlock it by deleting the contents of the mozilla.cfg file. (source)
