at the end What do these words reveal about the ways in which Scrooge’s feelings have changed?

Do you mean at the end of the whole play in Stave 5?

yes

Scrooge is truly a dynamic character. He changes at the end of the play. He is effectively "born again" with the spirit of Christmas. Where he used to walk with back bent in fatigue and morose, he is now jumping around like a child full of energy and brightness. Giving is now Scrooge's business instead of taking. His words are happy and enthusiastic.

“I don’t know what to do!” cried Scrooge, laughing and crying in the same breath; and making a perfect Laocoön of himself with his stockings. “I am as light as a feather, I am as happy as an angel, I am as merry as a schoolboy. I am as giddy as a drunken man. A merry Christmas to everybody! A happy New Year to all the world. Hallo here! Whoop! Hallo!” stave 5