Did Queen Elizabeth 2 change her name?

Answer 1

No. She was christened Elizabeth Alexandra Mary Windsor. Upon marrying Prince Phillip who had adopted the surname Mountbatten from his mother and dropped his Greek and Danish titles she continued to officially use Windsor. All descendants are still titled Windsor but an order issued in 1960 allowed descendants of her not royally titled to be titled Mountbatten-Windsor. Her children however despite being royally titled have used the surname in marriages and other circumstances but do not hold the surname officially in a title.