The style of the target list can either be Column Stages or Drop Down Stages.  To change the style, click Style on the target list menu bar and click either Column Stages or Drop Down Stages

The Column Stages style displays all of the stages in columns on the target list, enabling you to see the stages that have been completed and not completed. 

The Drop Down Stages style only displays the highest stage completed.  To mark another stage as completed, you simply click in the ‘Stage Completed’ box and select the recently completed stage.