I am using the theme Tarski which offers a sidebar and Widgets. I would like a lot of information in my main sidebar, with a much shorter sidebar for pages and posts. The Widget area offers this option, but no matter what I do every post and page still uses the default sidebar.
How do I get the "Post and page sidebar" to actually be used? I don't want a long sidebar on posts because when the post is short the user has to scroll through a bunch of empty space before getting to the comments.