By default, as you read new Discussion posts, Canvas will mark them as read (changing the indicators from blue to white) as you scroll down the page. However, you can manually mark each posts back to a read or unread state.
You can tell Canvas not to automatically mark all your posts as read in your Discussion settings.
Note:
In Course Navigation, click the Discussions link.
Click the discussion you want to view.
The read icon indicates the reply has been read [1]. The unread icon indicates a reply is new or unread [2].
To change a read post to unread, click read icon next to the post you wish to change.
View the post now marked as unread.
To change an unread post to read, click the unread icon next to the post you wish to change.
View the post now marked as read.
Note: If a post's state is manually changed, the post will not change states (become read or unread) unless you manually change it again.