Hearing a serial number (?) when connecting to headphones

When connecting Bluetooth headphones to my Forerunner 965, the voice prompt says a long number (perhaps a serial number?). The numbers and letters are spoken so fast that it sounds like gibberish, for example, “connected to… rev21280903702.” I have renamed my watch using Garmin Connect. Is this normal, and how can I rename my watch so that I don’t have to hear this every time I connect?