In all honesty you probably just didn't prepare well enough. I am a nervous test-taker so in college I had to spend a lot of time preparing for exams. The problem was I was very lazy, so freshman and sophomore years I really didn't "get it" and never tried hard to study. I knew the material from in class but I'd drop the ball on the exams.
My last three years (I changed majors two years in) I "got it" and preparing for exams meant setting aside a minimum of an hour per night to study. As I actually got close to exam dates I would spend a few hours at the campus library going over material.
As the classes got tougher I had to devote more time to them. Auditing took a lot of time because it was very comprehensive... everything you learn in all preceding accounting classes is applied in auditing, so if you were weak on a certain subject three semesters ago you had to force yourself to learn it now. Global Financial Wealth Management was also tough because of all the elements of math, econ, investments, etc. I lived in the libary my senior year.
It was all preparation. It's easy to give up and be lazy if you think you don't get something. But be honest and ask yourself if you're really trying as hard as you can? The answer is probably no.