Suggestion - Clarifying the difference between registering for a course and registering for its exam
The following are three different (but related) concepts: attending a course, registering for a course, and registering for an exam.
I know that unlike in our department, in some higher education systems, registering for a course implies registering for its exam as well: a student who is attending a course must take the exam, or it will count as a failed attempt. Following the same logic, one cannot take the exam of a course he/she has not attended- this was how it worked during my Bachelor studies.
It is important for new students to know the difference, that they can attend few sessions of a lecture, realize the topic does not fit to their plan, and simply stop. In more unfortunate cases, one can keep attending a lecture until the very end, but not write the exam, and this is also allowed.
I believe once new students are fully aware of this matter, they can attend more lectures during the first weeks of their first semester, and eventually pick the subjects that fits their interests best.
Since all lecturers emphasize on the importance of registering for the exam with the Examination Office, I don't think there is much to worry about students registering for a course but not for its exam- I hope not!