#Here are the options available to you if you disagree with the top voted and/or accepted answer:
Your options #1 and #2 are acceptable but other answers have covered why #3-6 are not. Instead I will cover the range of options you do have within the SE system to deal with cases like these. In general, they can be used in any combination.
###Dowvote incorrect answer(s) and upvote better ones
Obviously the standard way to indicate an answer's quality is to vote, one way or the other. Obviously you have only one vote but you can...
###Draw attention to the post to attract other voters
There are several ways you can attract eyes onto the post:
- Post your own answer (see below) which bumps the question into the queue of active questions
- Start a bounty (including a custom message with the bounty pointing people to flaws in the answer may help inform voting)
- Point people to it in chat (you can even explain your issues with it there and people may look into it and vote according to their whims)
- Point people to it in Meta.Se (if there is a meta-worthy issue to address)
###Comment on the top/accepted/incorrect answer
Leaving a comment for the person who wrote the answer that is now outdated gives them a chance to review the facts and determine whether they want to change their answer accordingly or not. If changes can be made to the answer to accommodate the new information they can integrate that info into their answer and the answer should now be (more) correct. If the new information would reverse their answer then they might agree to delete it. In the rare case that an author realizes that their accepted answer is incorrect they can request a mod to delete it by flagging it.
If the author is no longer active, this has a low chance of working.
###Comment on the question
Especially when the issue is with an accepted answer, leaving a polite comment to the author of the question may let them know that you believe there is new information that may change which answer they want to accept. Of course they are free to not act on it at all if they do not want to for whatever reason.
###Post your own answer
If there are no correct answers to upvote, write your own! This also has a couple of non-obvious advantages: it bumps the question in the active queue (and maybe even in the Late Answers queue) which mean it might get more eyes, and it notifies the author of the question of the new answer which might get them to look at the answers again as well.
###Be patient
Sometimes the Stack moves slowly, so don't expect that your actions will necessarily have immediate results. But the idea is that, over time, the correct answer will win out, so just do what you can and then leave the rest to the system. An important idea on Stack is that no one person determines what is correct or incorrect, instead depending on the wisdom of crowds. It is just sometimes crowds take a while to work.