The Lookups Options screen allows you to define which lookup is used for any conditions on a specific field in your query.

To specify the lookup, select the lookup in the drop down list and press OK. If you do not want a lookup applied to this field, select "<No lookup selected>". If you have the relevant permissions, you can create a new lookup by pressing the Add Lookups button to open the Lookup Wizard.

Once you have selected your lookup options, press OK to continue.