Get old App signature (AI 1 to App AI2)

I have made an old apk file in the App Inventor beta. Now i want to release a new apk file from the App Intentor 2. Google Play Store is telling me, that I cant, cause the Signature isnt the same. 

How can I Fix that?

Searched for signature changer but it wasnt possible to change that...



in App Inventor Classic in the Projects screen click onto More Actions - Download Keystore

then in App Inventor 2: Projects - Import Keystore

now build your app again

Oh THX a lot!!!