How do I view all of a student's posts for a Discussion at once?
You can view all of a student's posts and replies for a particular Discussion by going to Manage Discussion and selecting View Results.
Then, click on the name of the student whose posts you want to see.
This will show you a list of all of the student's posts. From that list, you can also jump to another student or scroll through all the students in the Discussion.
Related: How do I grade a Discussion inside of the Discussion activity?