There are 4 things to can do to a notification message when you get it (appeared yellow): Pin, mark as read/unread, clear or snooze it.
Mark as read/unread:
Snooze & Remove Snoozing:
Snoozing lets you turn off the alert only for a specific span of time and then automatically reappear as an unread update.
1 - Hover the mouse to the right corner of the notification message.
2 - Click on the "clock" icon.
3 - Select the duration or time & date you wish to hide it.
If you want to remove/extend the snooze, find it under the "Snoozed" tab of the Notification Feed, hover to mouse to the right corner of the message to edit it.
Clear & Restore:
Clearing notifications can be understood as archiving them. Once they are cleared, you can go to the "Cleared" tab in the Notification Feed to restore them.
Pinning/Unpinning:
Pinning notifications is a good way to pick your own priorities. This ensures that you never lose sight of the most important updates.
