Enable Status Change Notification

1. Go to the Manage apps section in Slack.
   

2. Search for the Jira app.
   

3. Search for the channel you want to edit the integration for and press the edit button.
   

4. Scroll down to the Status Changes section. Then Change the first on to * -> * like in the image below.
   

5. Scroll down and save the changes.

6. Create a test ticket and test the notifications.