I recently decided to update the email address I was using with my Norton account - unfortunately, this resulted in, according to Norton Support, 'an inability to sync ID vault to the re-named profile' and, basically, I lost the vault completely. I had to start again from scratch.
Fortunately, I had backed up the vault info fairly recently and was able to restore that to a newly created vault without too much loss.
However, if you are thinking of updating your contact detials then make sure you do a backup and prepare for the worst!