Many of the input fields consist of lists of all the possible values of that parameter presently stored in the database. For these fields multiple selections are allowed and the query will return visits that match any of the selections. You can select from any number of the input fields, the survey visits returned will match all your selections.
Press the "Submit Query" button to execute the query or the "Reset" button to clear your selections. These buttons are repeated at the bottom of each section of the form.