Possible Duplicate:
Is it poor form to switch accepted answers?
Assume I post a question and others answer it. I am waiting for serveral days, I choose the best one.
As time goes, another answer comes and I feel it is the best now.
Is it polite to switch to the newest one? I am worrying the previous person feel disappointed if I do this.
There's nothing wrong with switching to another answer if that answer is better/more complete.
However, if you want to be polite, you might want to leave a comment on the person whose answer you're switching from on why you're doing so, if only because there's currently no way to know which answers lose their accepted status, and some of us are quite obsessed about our shiny Internet points reps.
Don't worry too much about this. The odds will be good that the previous answer mark receiver will agree with your choice. The odds are even larger that he'll never notice, there is no good way to find out that you lost an answer mark. There is no notification for it, you'd have to watch the rep report like a hawk and keep copies so you can compare. I seriously doubt anybody ever does that.
Marking the best answer, even a late one, is appropriate in any circumstances.
