1. To reset customizations to defaults, first tap the Paintbrush:
(Note, if you don't have the Paintbrush button in your Timer screen, you need to purchase the Customization feature. You can do this by tapping the Store button at the top of the main menu.)
2. Then tap "Reset To Defaults":
3. Then tap the customization you want to reset:
4. Then tap the scope that you want reset it for:
That's it! The customization is reset to its default settings.