Sometimes the update does not cause a factory reset. But they're are times when after the upgrade, phone behaves weird... like battery drain, etc. This is usually sure to apps not behaving after the update.
It's usually quite hard to pinpoint which apps is being naughty.
so advise for major updates (different dessert name) is to do factory reset.
You should have no problem reinstalling fantasica and using back the current username.
Visit the strange ONE item stall