Parcel Feature Class Search Preferences are only used if you have selected to search the Parcel database instead of the Customer database. In order to be able to search the parcel database instead of the customer database, you must define the following fields:
The address search is performed using a geocoding service. Parcel feature classes may be geocoded the same way a street centerline theme is geocoded.
Name of Geocoding Service to Use:
This geocoding service is a system-wide setting and the service must be loaded into the project you are using. This service name will always start with the user that created it, and is exactly as it appears in ArcCatalog under the Geocoding Services Heading.
To learn more about creating and maintaining geocoding services, look in the ArcGIS desktop help under Geocoding Addresses > Geocoding Services
in ArcCatalog and Managing geocoding services in ArcMap.