How are you looking to modify it? If you want to change which field are shown for each item, then yes, you can modify those. Look in the Admin Console ("Tools"->"System"). Then click under "Presentation"->"Search" and double-click the item you want to modify (e.g. Service Calls). In the window that pops up, find the box called "Standard Search" and click the button to its right. You can here select the fields you want to show up in the search and re-order them.
You can also change the default view to use for search results on this screen I believe.