To set up a search screen to always have certain fields filled in (such as the County or Towns):
Open a search and populate the fields that you want set up as your default.
Click the little gear icon in the upper right (under the Results tab):
Click the top link to set the specific criteria as your default starting point for that type of search:
Search screens are customized individually. For instance, if you have set up custom criteria for a Residential search, those customizations will not be applied to the searches for the other property types (Cross Property, Land, etc.). You have to do each property type search individually.