The Echo Dot and Dot with watch are not compatible with each other.
Tap the Devices tab in the Alexa app and select the device you want to control.
To add a new contact, tap the Add (+) icon in the top corner. ..
Tap the Set Up Audio system button to configure your audio system.
You will see a list of Echo speakers. Choose two of the same type of speaker to stereo pair.
The speaker channels will depend on the placement of each speaker in your room.