Accounting question for people in accounting careers...?

Right now, I am majoring in accounting. I understand that with accounting, you either hate it or love it. Well, I love accounting and for ACC I, I breezed through it with no problems at all. Now, I am taking ACC II and I'm not grasping the topics as easily as I was in ACC I. (I'm taking these online) I'm sure that it is normal with some topics in accounting. But I was just wondering, are accounting careers like careers that you have to know like the back of your hand or is it as long as you have a good understanding on most things?