Mark channels as unread
If you read messages in a channel, but don't have time to address them right away, you can mark that channel as unread. Hover over the channel name in the channel sidebar, select the More 
option, then select Mark as Unread.
If you read messages in a channel, but don't have time to address them right away, you can mark that channel as unread. Hover over the channel name in the channel sidebar, select the More option, then select Mark as Unread.