I have seen a lot of explanations about the translation of the word 'about' but I cannot understand it very well, so I'd like to know in some of these cases (including the one of the title) what is the proper German word to use:
That is about you (In the sense of a statement or a thing which is about 'you', like a contract or something like this)
That letter is [talking] about you (There is something written about 'you')
We were talking about you and your wedding
If the second example's answer is 'um', and why a translator (Google Translate), would give me the translation of the first example as "Es geht um dich"
PS: The sentences in the yellow boxes are the sentences for which I would like to know which translation of 'about' I should/could use.