It seems that Firefox does not sync all settings the way for example Chrome does. In Google chrome one can expect absolutely all settings to sync across browser instances instantly. In Firefox only parts of the settings are synced. This makes Firefox unreliable and inconvenient because it is not apparent to the user which settings are synced and which are not. Here is my experience: - I made a new Firefox account - Signed in - Made sure syncing is on for: * Bookmarks * Credit cards * History * Add-ons * Logins and password * Options - Added some add-ons, added some bookmarks - Customized the interface - Changed some Settings - Opened a Windows 10 VM - Installed Firefox 83 (so both computers have the same version) - Logged in with my Firefox account - Waited for the sync So far I can see that my extensions are synced and my bookmarks. However there are some things that don't sync: - Customization for controls, buttons and toolbars - Default search engine - Alternative search engines - Settings for "Firefox Data Collection and Use" There might be more settings that don't sync, which I have not tested. Is this behavior expected? If so I might switch back to Chrome. Syncing only certain settings defeats the purpose of syncing, at least for me. Also is there any list or information about which settings are syncing and which are not?