Your game progress can be connected to your Game Center account (on iOS) or the Google Play Games account (on Android). Make sure to sign in so that you can restore your best score whenever you reinstall the app or switch to a new device.
On iOS
Step 1: Launch your Settings app.
Step 2: Scroll around and look for "Game Center". When you find "Game Center", click it.
Step 3: Enter your Apple ID (it's an email address) and your password.
Step 4: Click "Sign In".
On Android
Step 1: Launch the Play Games app.
Step 2: Select the Profile tab.
Step 3: Click “Sign in”
If you are not connected to the Game Center/Google Play Games, you will need to start again from the beginning when you reinstall the app or switch to a new device.