One-to-one time. Discipline and character actually comes from relationship.
First of all, we are not the Holy Spirit. They are the parents and not the other way around. We can't correct, just pray for your parents and allow the Holy Spirit to do all that convicting. So don't talk to them about politics if they told you not to and haven't reach the stage where they are convicted about it -- and no, it is not your job to convict them about anything.