How to update time of an Android notification

You're probably looking for NotificationCompat.Builder#setWhen(long). Supplying it with System.currentTimeMillis() should update the timestamp to the current time.

In addition if you want that timestamp to appear on Android N or higher, you need to call NotificationCompat.Builder#setShowWhen(true) at some point because it defaults to false.

Source: https://developer.android.com/reference/android/app/Notification.html#when