Where does extra outside scholarship money go that isn't used in cost of attendance?

Depends on the school. Talk to the bursar’s office and see if they can “hold” money for summer programs and/or study abroad if those interest you. My D is slightly over COA for 1st year, although the outside scholarship won’t be sent until after she’s been in school for a while, so supposedly it’s going to be applicable to a summer program she hopes to do next year. (I’m not holding my breath, though.)