Conversations provides multiple ways to filter posts in the left-hand topics list. 

Directly above the left-hand topics list, there are two drop down menus. 

The left drop-down menu allows you to sort posts by tag. When you select a course tag from the drop-down menu, only the topics associated with that tag will appear.  If you wish to view all the topics in the left-hand list, be sure to select the option Tag: any. 

The right drop-down menu allows you to filter posts by category. When you select a category from the drop-down menu, only the topics associated with that category will appear. You can filter topics by those you have bookmarked, unviewed questions, answered questions, and moderate posts. If you wish to view all the topics in the left-hand list, be sure to select the option Filter: none. 

The search bar located at the top of the right-hand display column, to the right of the filter-posts drop-down menu is currently disabled.