Search engine preferences are stored in a completely separate file, so that could explain why Sync doesn't pick those up. The '''browser.backspace_action''' preference is stored in prefs.js, but there isn't a corresponding sync preference. You can see what I mean in this example: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk. (2) In the search box above the list, type or paste '''homep''' and pause while the list is filtered If you have set a custom home page, you should see the address here: '''browser.startup.homepage''' The preference for whether to sync your home page (normally true) is: services.sync.prefs.sync.'''browser.startup.homepage''' ''I don't know if you can create your own sync preferences, or whether they would be ignored. Haven't ever tried it!''