I am using a Qualtrics date javascript library, mm/dd/yyyy but need dd/mm/yyyy. Can you help?

Qualtrics.SurveyEngine.addOnload(function()
{  
 //Set years you would like to have available   
 var yearFirst = 1900; //min is 1900
 var yearLast = 2049; //max is 2049  
 //This remains unchanged
 var qid=this.questionId;  
 var day=document.getElementsByName('QR~'+qid+'~1')[0];
var mo=document.getElementsByName('QR~'+qid+'~2')[0];
 var yr=document.getElementsByName('QR~'+qid+'~3')[0];  
 var days=day.getElementsByTagName("option");
var mos=mo.getElementsByTagName("option");
 
 var yrs=yr.getElementsByTagName("option");
  
 //hide impossibles
 
for(i=32;i<=150;i++)
 {
  day.removeChild(days[32]);
 }
for(i=13;i<=150;i++)
 {
  mo.removeChild(mos[13]);
 } 
 var j = yearLast-1898;
 for(i=j;i<151;i++)
 {
  yr.removeChild(yrs[j]);
 }  
 for(i=1;i<=yearFirst-1900;i++)
 {
  yr.removeChild(yrs[1]);
 }  
 function fixer()
 {   
  day.options[30].disabled=0;  
 day.options[29].disabled=0;
 
  day.options[31].disabled=0; 
  if(mo.selectedIndex==2||mo.selectedIndex==4||mo.selectedIndex==6||mo.selectedIndex==9||mo.selectedIndex==11)

{
   day.options[31].disabled=1;
   if(day.selectedIndex==31){day.selectedIndex=30};
   if(mo.selectedIndex==2)
  
   {
    day.options[30].disabled=1;
    if(day.selectedIndex==30){day.selectedIndex=29};            
    if(parseInt(yr.options[yr.selectedIndex].innerHTML,10)%4!=0)
    {
     day.options[29].disabled=1;
     if(day.selectedIndex==29){day.selectedIndex=28}; 
    }     
  
 else
    {
     day.options[29].disabled=0;
    }
   }
  }   
 }
 yr.onchange=function(){fixer();};
 mo.onchange=function(){fixer();};
});