The employer is curious as to why you are leaving your current role and if that issue will be present in this position. They are also looking for what makes you happy and if this position is a fit for you. They are wondering if you are adaptable and if you get upset about minor details. You want to answer this question honestly and with balance. You don't want to throw individual people out as reasons why you are unhappy or challenged. That would sound as if you cannot get along with different personalities. The best types of answers involve a lack of potential for growth, or a change in responsibilities from your current role, or a desire to improve on a different skillset for you. It is best to avoid talking about schedule unless you are on third shift and need a dayshift position.