iMessage notifications coming on both Apple Watch 4 and iPhone XR

Hello,

When I first got my Apple Watch 4, iMessage, and other notifications sounded through my Apple Watch only. As I understand it, it is considered the dominant device when both are on.

Since the last update, notifications are sounding on both the iPhone and the Apple Watch. How do I go back to the Watch only, when I am wearing the watch. I don't really want to have to remember to silence and unsilence my phone everytime.

Thanks for any help.