You can adjust the filters and settings for your Contact Lookup Tool by opening the tool in your CMS site's Folder structure.  You will now see three tabs, one of which is Search Criteria.

Open this tab and you will find multiple options for editing and adjusting the search tool's setup.  You can add or delete fields, alter what search features are available, such as the ZIP Locator.

You can also set the search tool to look over individual or organizational records, but not both.