Scrooge has such a hard time watching the scenes from the past since those are bad memories for him that he does not want to reminisce. There a lot of different versions of the story but I will use details that are pretty general. In the story when Scrooge resists his past, he sees it from a different viewpoint now and sees how he acted and treated people. This causes him to feel bad about it and want him to leave those happenings behind. Hope this helps!
