I'm unable to select and saveany text filters except for "Filtered HTML".
As far as I know, this functionality is "broken" in D7, meaning that the UI is at least misleading. Here's some discussion https://drupal.org/node/1003262

What you can do is change the order of text formats at admin/config/content/formats. The default text format available to users will be according to permissions and the order of text formats.

Also see http://drupal.org/project/better_formats. That will give you more options.

Also see How do you set a default input text format per content type?