They would belong on the tax return for the year to which they apply, so you'd have to amend your tax returns for those years. If you were claimed as a dependent on somebody else's return (like your parents) during those years, you wouldn't be entitled to claim any educational expenses on your own return.
Here's information on preparing an amended tax return. It's too late to amend your 2012 return if it was timely filed (April 15, 2013). 15, 2017, is the last day to file your 2013 tax return to claim a refund; if you had an extension, your deadline is October 15, 2017.
**Mark the post that answers your question by clicking on "Mark as Best Answer"