Hi mable, I understand that you have obtained a new computer, that is awesome! However I also understand that your cousin is now trying to connect the sync account to the new computer. I am happy to help. There are a few things here I would like to clarify. One, is the older computer still accessible? If so, make a back up of the local profile so that your cousin has a back up. [[Back up and restore information in Firefox profiles]] Two, I do not know of a message that says "not synced, yet" can you please ask them for a picture of this. I would like to verify its not a virus. Three, the account will only actively sync devices that are attached to the account. If the previous computer has been removed, if you have not changed the password to your cousin's account it should merge what is synced to the cloud.