need advice

Hello, My wife and I three weeks ago accepted a 17 y/o boy into our home. He just came into the system two months ago, and will be 18 this summer. We were asked to take him in for one year until he graduates high school next spring. He spent a weekend with us and we all felt good about the placement. Since his arrival he has made a 180 degree turn. He refuses to do any of his chores, and he only sees things from a negative perspective. The plan that he is on is to help him transition into adult living, but he is not doing the necessary work that was set for him to accomplish in order to fulfill the goals he set academically. He told the agency that he is wanting to attend college and eventually become a professor. He told us that he only put that on paper to write something down, but he doesn't really have any plans to do anything. He doesn't do simple things like brushing his teeth, but he changes clothes three times a day. We recognize that some of this is acting out, but what are some suggestions you have for us to help address some of his issues with responsibility and personal care? Also, he told us that his therapy is a joke, and so he just makes up stuff to steer the therapist off the topics. We have told the caseworker these things, but we also want to do our part in partnering to see him succeed to our best ability in the year we will have with him. Thanks for your input.