In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button and select Settings.
. In the OptionsPreferences window, click on the Sync tab.
Click Set Up Firefox Sync
Under I already have a Firefox Sync account click Connect and the code to add this computer will be displayed.
and select .
. In the OptionsPreferences window, click on the Sync tab.