From your Momentum app, go to Cues
From the Cues page, click New Cue
Add a name for your Cue
Select trigger type to Opportunity Updated
In the condition requirements box, check the box changed?
Select field as Stage
Select operator as Includes
Select the value as Closed Won and click Next
Add any message that you want to show with the notification along with fields like Amount, Account name, etc. (one field is necessary to move on to the next step)
You can also add a GIF (Using tags & GIF library) and click Next
Chose the type of notification from the drop-down (public message, deal room, private)
Select the Channel
Click on Create
Well done! 🎉 You will now be notified when the opportunity is closed lost along with the reason.