If our personality is the real us and remains down through the incarnations what about someone with a bad personality, can this be altered?

The personality always remains, together with individuality and memory, these being the factors of selfhood. However, personalities can be changed and someone with a bad personality can always choose to make a change for the better. Whatever the personality at transition, that is the personality with which one will reincarnate, but one will be given opportunities to rectify any defects, and every effort should be made to do so.