Evaluations are meant to be simple -- easy to add and easy to use. To that end, they only have the few basic options you see here. If you want something that has more features (such as a specific due date), then you should navigate to the Coursework page and add an assignment. Assignments are a lot like evaluations, but they have a much more robust set of options for you and your students. You add and grade assignments on the Coursework page, but they show up here in the Gradebook automatically for use in calculating the final grade.