From your Admin portal, click on Online Courses.

There are two ways you can modify settings: Globally and on an individual course level.
Click the Settings tab at the top of the Courses list to change settings globally, or navigate to the course of your choice and click the Settings tab at the top.
Now if you are wanting to change the settings for an individual course you'll see that by default the global settings are applied:

You need to uncheck the global setting to then change it to something else. Keep it checked allows the global setting to automatically apply if changed. It's important to note that changing the global setting when a course has the global setting option unchecked will not make changes to that setting for that course.