This settings allows you to choose which search engine to use when you search through the search box on the right side of the window.
Crawler Toolbar allows you to pick either Crawler.com or MSN.com (default search engine).
To change this settings, follow these steps:
Go to Crawler Toolbar Settings.
Select the "Services Settings" tab.
Click on the "Settings" button within the Search services section.
On the "Advanced" tab, select the search provider.