Problem with page title

IdeaStream is not using WordPress pages. I advise you to avoid using this else you should see a slug conflict in IdeaStream setting. If you need to change the main archive page title, you can so it from the same area.
If your theme is forcing the term archive to show, then you can add an ideastream.php template : see https://github.com/imath/wp-idea-stream/wiki/Ways-to-customize-the-plugin-from-your-theme