The following script can change the label
widget.on('ready',function(e, args){
$('[id="' + args.widget.oid + '"]').find('span:contains("Grand Total")').text("YTD");
$('widget[oid="' + args.widget.oid + '"]').find('span:contains("Grand Total")').text("YTD");
})
If there is only one row you can use the following script:
widget.on('ready',function(e, args){
$('.p-grand-total-row-head').find('span:contains("Name of Value")').text("Grand Total");
})
