Rule 1: Focus on yourself, not what others say or do.
Before you try to change the world you go and clean up your own room. If someone or something pisses you off, rather than trying to teach them, you figure out why it bothers you and see what you can do to not be bothered by it.
Only go and privately point stuff out if it's a close friend/person and you have enough trust built up to be able to resolve misunderstandings if there are any. With strangers/acquaintances, it's better to avoid those kinds of things as you 1)don't know them well enough to understand what they mean, 2)since you aren't close, it is plainly not your business, 3)you don't know what kind of person they want to be either, so you can't give them advice they need.
If being around someone makes you upset all the time, rather than raging at them, you be around them less or cut them out from your life altogether. Trust your gut when it comes to this. You like yourself when you are around people you sh