Getting a Rank Order question to only allow respondent to rank only 3 of the 6

Look at the stetup below:

Thank you, but the respondent is still able to select 4-6. We want them to rank their top three only, in the order of importance to them.

Is you question this way:

Yes, the problem we are having is that if a person selects 4 or more, it is difficult to remove the extra selections.

Hi,
What you probably want, is the survey to show only 3 columns ... so it's not even possible to select a fourth. I had the following JavaScript and that seemed to work fine, except when I used a large number of items (20+) en a large number of questions with this setup (but different items, obviously).
Qualtrics.SurveyEngine.addOnload(function()
{
/*Place your JavaScript here to run when the page loads*/
for(var i = 3; i < 100; i++){
jQuery("#"+this.questionId+" tr.Answers th:eq("+i+")").hide();
   jQuery("#"+this.questionId+" .ChoiceStructure tbody tr").find('td:eq('+i+')').hide();
}

So I'm not sure if it works without problems, but will probably help you on your way. Without custom coding, it's not possible to get a proper 'select your top 3' question type.