If you are not able to update the game at store, please try following the steps below.
■ Google Play Store
1. [Settings] > [Apps] > [Google Play Store]
2. Uninstall updates, clear data, and clear cache.
3. Reboot your device and enter Google Play Store > Select ‘Agree’ at a pop-up message
4. Re-install the game.
■ App Store (iOS)
1. [AppStore] > [Update]
2. Drag down your update category screen to renew the list of updates.
※ If you play the game with guest account, all saved game data can be reset once you clear data & cache.
Please make sure if your game account is linked before following the steps above.