- Hover on a channel in your teams list and select More options
> Channel notifications 
.
- Choose from All activity, Off, or Custom—just as you would in settings. When you select Custom, a new window will open that has more options.
- To be notified about all your shown channels, select All activity
- To turn off all notifications for a channel, select Off.
- For the most control over your channel notifications, select Custom
Choose the Edit button next to the category to customize how you receive notifications for that category.
Categories include Chat, Meetings, People, and Other.
Note: By default, channel @mentions are turned off and all new posts will only show in Activity .