Html
super
is #you html element change data-you attribute
attr() And you can not have to change the data() method.
Try the following way:
console.log($("#you").data("you")); // Hello mean
$("#you").data("you", "yes change you atribute"); // yes change you atribute
console.log($("#you").data("you")); // yes change you atribute
examples of data http://api.jquery.com/data/