Hi! Please help?

I can't figure this out. I'm logged into the game on my old device - all progress is present.

I am logged into Google on my new device and I go into the game and the "Log In" icon isn't even in the Menu. It's wanting me to start from scratch and lose all my progress.

Both phones are Android - old phone is a Samsung Galaxy S3 and the new phone is a Samsung Galaxy S7. Do I need to uninstall from old device before logging in is an option on new device?

Advice please?

Thanks!