Any of my answer which is downvoted, how do I change it? I mean should I "edit" it or do what?
Because if I edited it the OP might not find that I have edited it, or will he?
Go ahead and edit it.
It will pop up to the top of the 'most recent' list. Sure, maybe the downvoters won't see it to change the direction of their vote. But other people might see it and upvote. (or not, "you pays your money and you takes your chances")