that's because
var img = $(".photo_medias").data("imagefull");
$(".photo_medias").attr('src', ""+img+"");
executes once on each click and it targets all the elements with the .photo_medias
class
to go through each one individually you can utilize .each()
function and this
reference
$('#GoList').on('click', function(){
$(".photo_medias").each(function() {
var img = $(this).data("imagefull");
$(this).attr('src', ""+img+"");
});
});