When you're still in high school or even in college, adults won't always take you seriously. Yes, you're only a few years away from legally being considered an adult, but your parents won't always remember that. They've raised you since you were little, so they're used to looking at you like a child. In order to get them to change that attitude, you'll have to do a few things.
If you're always talking back to your parents and cursing them out, they're going to see you as immature. You have to treat them with respect if you want them to do the same. The next time they give you an unreasonable curfew, try sitting down with them and having an adult conversation instead of raising your middle finger. It's all in your attitude.
If you get a traffic ticket, don't create excuses about the cop doing his job incorrectly. Apologize for blowing the stop sign and promise to be more careful in the future. Even when you're thirty, you're going to make mistakes. It's how you deal with them that determines how others will view you.
Don't give your parents a reason to think poorly of you. Do your homework, get good grades, and avoid detention hall. Even if school isn't a big deal to you, it is to your parents. If they see that you're doing well, they'll know that you're responsible and can be trusted.
If you have enough time to juggle school, a social life, and a job, then you should do so. Your parents won't view you as a child if you can buy your own video games instead of asking them for cash every time you leave the house. Landing and keeping a job is another great way to prove that you're responsible.
When your parents actually trust you, don't let them down. If they leave the house for a weekend, don't let them come back to see the place trashed. If they allow you to stay out until two in the morning, don't come home wasted. If you do, then there trust in you could vanish.
Adults don't always appreciate what's in style nowadays. That means that they don't want to see you wearing your jeans halfway down your thighs. When you go out with your friends, dress however you please. But when you're going to a family dinner, dress conservatively.
If you want your parents or teachers to respect you, the way you speak to them is incredibly important. Avoid cursing and using slang. Speak to them like you would speak to your boss. That doesn't mean that you can't joke around with them and tell you about your day. Y can, but you just have to remain respectful while you're doing so.
No matter how young you are, you can convince others to treat you like an adult by behaving in a certain way. You just have to watch how you dress and how you act when the people you want to impress are present. Do your parents treat you like an adult or do they still view you as a child?