<p><a href="http://meta.stackexchange.com/q/120568/189912">The person who asked the question</a> can <a href="http://meta.stackexchange.com/a/5235/189912">change their mind about the accepted answer at any time</a> by clicking the check mark again, or clicking the check mark next to another answer.</p>

<p><a href="http://meta.stackexchange.com/a/105815/189912">Moderators cannot override this</a>, though obviously anybody with sufficient access to the database probably could...and <a href="http://meta.stackexchange.com/a/60214/189912">almost certainly won't</a>.</p>