Am quite confused here. I just had a question Progress Dialog dismissing problem for which I had to set an bounty of 50 reps. The thing is that, I believe I have accepted a wrong answer first and have offered my bounty to a a non relevant answer. Though I am capable of changing my accepted answer, I am not allowed to re offer the bounty to correct answer. I know this is late, but this might help someone in the future. Can anyone clarify this.
Once the bounty is awarded, it's permanently awarded:
Incidentally, neither of those pages say it, but you have 24 hours after the expiration of the bounty to make your award: A grace period of one day to award the bounty after expiration (without remaining featured, of course)
Note that accepting an answer is a different and unrelated action. You can read about the background here.
(there is one edge condition: if someone accepts an answer during the bounty period but fails to award the bounty, we assume they wanted the accepted answer to have the bounty; this would occur 24 hours after the bounty period is over.)