Once you have set up a class and your students have joined it, you have the option to either control topic filters yourself or allow your students to control them.
Select the course and then the class. Then click More actions and select Configure class.
Select Topic filtering from the options.
Set which topic filters you want to apply or choose the filter mode:
1. Teacher Controlled - The teacher is the only one able to set topic filters
2. Teacher Guided - The teacher can set topic filters, but students can also filter, but only on the topics chosen by the teacher.
3. Student Controlled - The student has free reign to set their own topic filters.