Firefox

Hi guys! I'm trying to disable Firefox' menu that shows when you right click. Sometimes, depending on context (ie, right click on a youtube video) you might get a webpage menu. But Firefox places their right click menu on top of the web's menu, blocking everything. I want to disable this, so the website/extension takes precedence, and the menu doesn't show in this case.

I see on some pages the option should be: dom.event.contextmenu.enabled, which should be set to TRUE in order to let webs or apps take precedence. It is already set to true, and yet FF keeps placing their menu on top of the website's. What else can I check?

EDIT: Just in case, there seems to be also an services.sync.prefs.sync.dom.event.contextmenu.enabled, which might be synced from my mozilla account? Not sure how this one should be set.