* How do I select the data that I want to sync?
* How do I reset my Sync data?

Sync isn't meant to be used in that way, so you have to be careful and check the Sync settings before saving the Sync setup to make sure that you aren't replacing the data on the Sync server with your current personal data. You can click the "Manage Account" button and choose Reset Sync to select what to sync. * Replace all data on this computer with my Sync data See Managing your Sync data: * How do I select the data that I want to sync? * How do I reset my Sync data? * https://support.mozilla.org/en-US/kb/how-do-i-manage-my-firefox-sync-account