Fact: All colleges have an enormous number of rules and policies that cannot be broken. Often the reasons for these rules are based on legal decisions or policies of the accrediting agency.
Many of these details are available at this website: AU Academic Information & Guidelines. Here are a couple of items that you may need:
First, the official statement:
Students may add and drop courses via Webadvisor until the semester starts. After the semester begins, students can continue to drop and add courses until the drop/add deadlines listed in the academic calendar. After the drop deadline, students can withdrawal from courses until the withdraw deadline and will have a grade of "W" appear on their transcript.
OK—that is confusing. Here's what it means for the Fall 2019 semester:
If you drop a course, it simply vanishes from your transcript. If you withdraw from a course, your transcript will show a "W" grade, but your GPA will be unaffected.
One obvious reason is that the course did not turn out to be what you expected: You wanted a course that would teach you how to create a sculpture, but this turned out to be an art appreciation course.
A more important reason is that you discover you cannot handle the workload, either because of schedule problems or because you were not properly prepared for the course. You simply bit off more than you could chew.
A grade of "W" will cause a lot less grief on your transcript than a grade of "F" so don't just stop attending.
The Incomplete is a temporary grade given to a student who has completed most of the course and has a passing grade but is unable to complete the course for major reasons beyond his/her control (such as a serious medical problem). The Incomplete is not intended for students who simply did not get around to doing all the work during the semester. The University academic calendar lists the final deadline for making up Incompletes each semester.
The official academic calendar lists the date when you can start signing up for next semester's courses. (In our case, it is Monday, November 11, 2019.)
You would be wise to sign up for courses as early as you can. Courses fill up quickly, especially if you need a particular course or a particular time slot. (That great course might well be unavailable by Monday evening!)
Our supervisors discourage us from accepting overloads, but if the course is full, you are not necessarily out of luck. Students come and go from courses very frequently in the early days of registration, so check Webadvisor often. You might get in after all.