I need to add a title when fancybox 3 opens the window as iframe. I tried to add with helpers or other but no result

Title doesn't show. Any help? The link is this one:

 <a onclick="viewdetails();"  data-caption="caption here" title="Title here" >xxx</a>

and the function here:

  function viewdetails()
        {
    
 $.fancybox.open({

  width : 1280,
   height : 720,
   fitToView : false,
   autoSize : false,
   titlePosition: 'top',
   titleShow: true,

 src  : 'page.php',
 type: 'iframe',
 scrolling: true,

 opts : {       
         modal: false,
        afterShow : function( instance, current ) {  
        },
    toolbar  : false,

    smallBtn : true,
    iframe : {
    css : {
            width  : '1280px',
            height : '800px'
        }
    }

    }
});
    }