Click the Settings > General Settings > Reset Settings > Restore Defaults icon to reset all Settings and Hand Importing options to their original/default values.  What this does is delete the C:\Users\UserName\AppData\Roaming\HoldemManager\HoldemManager.config file and recreate it in it's default form.  This will NOT reset any of your AutoRate, Database, Filters, Scanner FishFinder, NoteCaddy, HUD Options and Popups, or Reports customized settings as these have their own folder in the C:\Users\UserName\AppData\Roaming\HoldemManager\ directory that are separate from the config file that gets reset.