If all of the answers would still be ok after your edit, then yes, go ahead. Be sure to leave a cool-off period — don't change your question while there's a high chance people are typing an answer. It's good to have answers that correspond to the question, and while it's normally up to answerers to ensure that, occasionally the asker can help. This shouldn't happen often; usually it's because the question was unclear in the first place, and you're clarifying it to be what people understood rather than what you meant.
If you decide to edit your question, it's ok to post a new question to ask what you originally meant to ask, if the new question is significantly better-worded or represents a next step on solving your problem: the first question helped you, and that second question is to help you further. Often in this case your new question should contain a link and short explanation of the old one (e.g. “I previously was advised to do <this>, but it turned out not to work because <explanation of why the answers to the first question didn't solve the problem>, so what can I do in this case?”), so that people can choose not to bother repeating old material.