If you have an app that is frozen or not functioning correctly, start of by pressing the RESET button on the back of the tablet.
Turn the tablet back on and try the app again. If it still doesn't work, you may have to uninstall the app and reinstall it from Google Playstore.
To Uninstall an App:
Simply push the Settings icon on the main screen, scroll down to Apps, choose the downloaded application you wish to uninstall, click on it and there is an option to Uninstall the App.
To Reinstall an App:
Simply go to Google Playstore. Type in the App and hit Install, follow the instruction.
If the app is still not working, you would need to contact the Apps developer and inform them of the issue so they can resolve it on their end.