To clear your cache, please follow these instructions:

-Tap and hold the icon in the app drawer
-Drag it to "App Info"
-Tap "Clear Cache"

When you load the game once more, you may be logged out of your Facebook/Google+/Username account. If this happens, please go to the Account Info page and log in once more after playing through the tutorial. This will restore your progress.

If you run into any issues, let us know and we'd be happy to assist you further.