I was listening to a song and I got confused with tú eras and eras tú. Also, I was confused about the conjugation of the verb cambiar in the following sentence, "Llegaste tú y todo cambio" Why is combiar conjugated with "yo" not "tu" or "el/elle" here?
That's the link of the song: http://www.youtube.com/watch?v=4kwz8CuZgkI