Ugh...back again, with more crap that drives me nuts when typed by grown-ups...
They're = another contraction (just like you're = you are), short for "they are". Unless you can replace it in the sentence with "they are", DON'T USE IT!
There = a place. That's it. If you're not describing a place, DON'T USE IT!
Their = a possessive pronoun. Unless what comes after it is something that belongs to something/someone, DON'T USE IT!
Ugh. These are not hard, people, none of them are advanced or complex thoughts to process. If you finished middle school with a passing grade in English, we should not be needing to have this conversation. Figure it out, or put away the keyboard. Seriously. Seriously seriously.