device settings notification count

Hi guys,
I dig all the sdk guides and i cannot find what i'm looking for. For watchface, my notification count does not refresh. I put my code into the onUpdate function
but after one minute the notification count still the same even if i clear it on the smartphone. Some watchface on the app store clear the notification at the same time the user clear it on the smartphone. What i'm missing here?? I see nothing in the sdk guide that can help me.
Do you have ideas?
Thanks