Settings should be preserved across upgrades, so this isn't what we'd expect. What version were coming from? If you were coming from version 10.0 or later, there's a backup of your settings from before your upgrade saved to your USB memory stick. Generically, it sounds like at least your fuel calibrations might have an issue. What do you see where your fuel level sensors used to be? Also, when you press PFD > HSI SRC, does that have no effect on the HSI?