1. Open the phone, find the application icon of Cool Dog Music on the phone desktop, and press and hold the icon.

2. In the pop-up menu, select or click the "Application Information" option. The application information page of Cool Dog Music will open.

3. On the application information page, find the option of "Permission" or "Apply for Permission" and click Enter.

4. In the permissions page, look for the option of "Notification" or "Notification Permission", and then click Enter.

5. Ensure that the notification option is enabled. If it is already enabled, you can try to turn it off and then enable it again to ensure that the permissions take effect.

6. Go back to the mobile phone desktop, reopen the cool dog music application and play a piece of music.

7. Drop down the notification bar of the mobile phone, and you should be able to see the playing status of cool dog music displayed in the drop-down menu.