Same. So u need to turn on Bluetooth, connect your Garmin, sync, and the option to change password will miraculously appear. Frustrating but I just did it :)
In Garmin Connect app, you should not click on Garmin Pay which is located as part of the Left main Menu; but instead: on the top middle of your screen klick on your Watch face , and in that menu open the Garmin Pay. There is also option for the Pin change.
