NOTE: there is no way to sort users by section in Quick Eval - all users in a merged course are displayed in Quick Eval.

Please see the article How to Send Announcements in a Merged Course for how to send announcements to different sections of a merged course.

In a merged course you can toggle between all users and sections in throughout the course in tools like Grades, Classlist, Assignments, and Quizzes. Look for the "View By" dropdown. To sort the view click on the "View By" dropdown and click "Sections" then "Apply"

Next, click the "Sections" dropdown, click on the section you'd like to view, then "Apply"