Acknowledge a notification
You can acknowledge a notification as soon as it arrives, by taking action on the pop-up. Or, you can do it later from the Notifications panel.
When a notification arrives you'll receive a pop-up message like this:
You can see the notification message and the time the notification was triggered.
Select the green tick to mark the notification as read. The pop-up disappears.
Select the red cross to dismiss the notification. The pop-up disappears and the notification is treated as unread. You can deal with it later in the Notification panel.