So the statement “changed a lot” merely means Julie has shaped herself according to Gayathri’s liking.
Julie’s lie yesterday was bigger than all of them because she apologized which were just words. I remember Oviya saying ask a sorry and we can be friends. That is what a gem of a person says even after she was insulted and cheated upon, her character assassinated because of Julie. After Julie apologized to Oviya in front of Kamal, everyone knew that all the housemates trained her to apologize and to just move on.
However, that was never Julie’s intention because it wasn’t heartfelt. She never accepted her mistake in the first place to even apologize. Like Aarav rightfully said, “What 5-second video is she even asking for? In 5 seconds you can only blink her eye.”