Let's get this straight.

Your : This is a possessive adjective. It is used for ownership

ex. Is that your ball?
ex. Your hair is pretty

You're : This is a combination of you and are.

ex. You're so stupid.
ex. You don't know what you're saying.

There : Used to tell where something is.

ex. Is that your ball over there?
ex. My house is over there by the big oak tree.

Their : Possessive adjective

ex. Their parents weren't home
ex. Why would their opinion matter?

They're : Combination of they and are.

ex. They're playing hockey
ex. I don't know what they're saying

If you make a mistake, then you're just looking stupid.