Plus, in terms of graduating at a reasonable rate that can kill you. You end up in a situation where you don't have the right entry level classes to take the second level class in whatever you decided your interested in and you have to go back and take another class that isn't that much different then what you've taken.
If you are going to go that route, I'd strongly suggest that you spend a year or two at a community college (though I'll say that advisors at C.C. that I've heard of are AWFUL don't believe a word they say about transferring credits to other programs or your oppurtunities getting into other programs and the course aren't likely to be what you will see at 4 year schools), but you'll save somebody a lot of money.
My suggestion, on this topic is to talk to somebody that work in a particular fields. Do some reading in different areas related to careers. Try and get a feel for what you might want to do based on that, and then go from there. You also don't have to go in day 1 and make a decision that you can't change. You do have some time (I just wouldn't wait to long and I'd suggest actually starting with a major or at least genreral direction w/o being afraid to change your mind later) and most colleges do have career services and things like that so talk to them.
Try and pick something that seems like it might be a good fit and try and stick with it some. Don't ditch it because you don't like the first class (necessarily, though as always there are exceptions to every rule). However, if it is clear, any where along the way that it isn't working, don't be agraid to get out. The other thing you don't want to be is that senior that's struggling to pass classes in a major those last two semester in a major that you don't like, but now have 3 years into and just feel like you have to graduate.
You said you've thought about accounting. Have you talked to any accountants? Where is the accounting field going? How much is it being taken over by computer programs and tax lawyers?
But in the end, if you have to, flip a coin and start moving in a direction.
In terms of intelligence and things, I've honestly found that it isn't as big a deal as you'd think. I have 6 siblings. Growing up, at best, I would have been put in the middle of the pack. I have PhD in biochemistry and teach at a university. My siblings include 2 H.S. teachers, 1 physical therapist, 1 middle management/costumer service like person, and 1 that has spent about 1/2 of his adult life in jail and the other 1/2 doing things that will cause him to go to jail if/when caught. Now everybody talks about how I'm the smart one.
In most cases, you can be successful IF you REALLY like what you are doing (in most cases. there are always exceptions, again).
Most schools will allow you to withdraw from a class with a W on your transcript even more than 1/2 the way through the semester. You don't get a refund though. If you are failing at the time of the withdraw that might be indicated some how (e.g. WF). Most places don't look poorly on a W, and even if you have major issues, if there is a reason and you do well after the fact it doesn't tend to be an issue.
I know a student that started off in an engineering program. Did AWFUL and was kicked out of the school. Had to take some classes at communit college to get back into college. Switched to chemistry. After the switch has a GPA over 3.8, but still had a really low total GPA and is going into a top 20 grad program in chemistry (also did really well on GREs).
An unrelated piece of advice. Some of the people you will meet in 4 years or more you will be asking to write you letters to go get a job or into some other program. When interacting with faculty/administration, ask yourself am I giving this person an impression that is going to help get this person to support me in the future.
A lot of people here will tell you are still young, but realistically in college from day 1 you are on an extended job/post-college interview because if you can't get good recs from the people you interact with when at college, you'll have issues getting those interviews.
Realistically, the visual of the sophomore sitting in the hall talking about how they got wasted the night before the big test and so didn't do well on the test doesn't leave you 2 years later when writing a letter for that same person.
This doesn't mean that mistakes aren't allowed or that you have to be perfect, but even in making a mistake you can make a good or bad impression based on how you made it, what it was, and how you recover.
(Of course, I'm a grumpy old man that believes that young people have to long of a delayed adolescence these days.)