I get asked a lot how to disable certain buttons in preferences like Make Firefox the default browser or the various buttons in the Startup groupbox. Firefox does have a way to disable these buttons, but it's not very obvious. This post will attempt to remedy that.

These buttons are controlled through preferences that have the text "disable_button" in them. Just changing the preference to true isn't enough, though. The preference has to be locked, either via the CCK2 or AutoConfig. What follows is a mapping of all the preferences to their corresponding buttons.

pref.general.disable_button.default_browser

Advanced->General->Make Firefox the default browser

pref.browser.homepage.disable_button.current_page

General->Use Current Pages

pref.browser.homepage.disable_button.bookmark_page

General->Use Bookmark

pref.browser.homepage.disable_button.restore_default

General->Restore to Default

security.disable_button.openCertManager

Advanced->Certificates->View Certificates

security.disable_button.openDeviceManager

Advanced->Certificates->Security Devices

app.update.disable_button.showUpdateHistory

Advanced->Update->Show Update History

pref.privacy.disable_button.cookie_exceptions

Privacy->History->Exceptions

pref.privacy.disable_button.view_cookies

Privacy->History->Show Cookies

pref.privacy.disable_button.view_passwords

Security->Passwords->Saved Paswords

pref.privacy.disable_button.view_passwords_exceptions

Security->Passwords->Exceptions

As a bonus, there's one more preference you can set and lock - pref.downloads.disable_button.edit_actions. It prevents the changing of any actions on the Applications page in preferences.

http://mike.kaply.com/2014/10/22/disabling-buttons-in-preferences/