→ Grammatically: "Seu/Sua", "Seus/Suas"(plural), is a possessive pronoun that refers to something that belongs to "ele/ela" (he/she), "eles/elas" (they). For example: "Ele pegou seu celular" (Literally: He picked up your cellphone = Meaning: He picked up his cellphone) / "Seus olhos são lindos" (your eyes are beautiful). "Seus olhos", in this case = her eyes, because you're describing one's eyes to other. And "teu/tua" is a possessive pronoun that refers to something that belongs to "tu" and "você/vocês" (you). For example: "Esta coisa é tua" (This is your thing) in this case, you're talking about his thing with him. → Colloquially: At least in Brazil, "teu/tua" "teus/tuas" are used in other contexts. Some regions such as the Northeast of Brazil, Rio de Janeiro and Espírito Santo, it's customary to use "teu/tua" as "seu/sua". In others, like São Paulo, "seu/sua" is used as a more informal/personal treatment. These forms are not the official forms of the language, but are widely used. In general, colloquially, it won't make difference. It's a useless rule since both works and nobody won't even notice. :)
"Os teus livros" can be used, as well as "teus livros".
But not "teus os livros", not in this case.
It's possible in more elaborated sentences, like the inversion of "os livros são teus???" --> "são teus os livros???". But that would translate to "are the books yours?" (not your books)