1. Go into the course that you want to edit.
2. Click the gear button located in the top right of the page.
3. Select "Course completion" from the menu. 
4. Click the "Expand all" button located on the right.
5. Scroll down to the section titled "Condition: Activity completion".
6. Toggle on each activity in that section that you want to require as a condition to complete the course.
7. Click the "Save changes" button at the bottom of the page.