Question about 2nd Person Pronoun in Don't Cry for Me Argentina in Spanish & Portuguese

So, I was listening to the versions of Don't Cry for Me, Argentina in Spanish & Portuguese and noticed that the second person personal pronoun varies throughout the song and, was hoping you could elucidate the reason why.

In Spanish it starts off with vosotros (debéis creerme, la fe que queráis conseguir, mi lugar vuestro es por vosotros luché) and in fact continues that way for the whole song, except for the chorus, in which she sings no llorés por mí, Argentina while the rest of the 2nd person personal pronouns in the chorus are also tú form. There are several aspects of this I find confusing. First, why would Eva Perón, an Argentine first lady, be addressing the Argentine public using vosotros? I listened to some speeches given by Evita and all of the plural 2nd person pronouns were ustedes, plus it is my understanding that besides poetic and biblical uses vosotros has been out of use in Latin America since sometime in the 1800s, at least. Is it simply vosotros in the song because it's first (and to my knowledge only) translation was sung by a Spaniard? Second question is why does she switch to tú for the chorus? The whole song appears to be addressed to the people of Argentina, unless I'm missing a subtlety in change of addressee. Is Argentina the nation different than the people of Argentina?

The Portuguese version is entirely vocês (peço me creiam, Que um dia irei merecer o amor que sentem por mim,etc) except the chorus, which as in the Spanish version, is entirely tu (Não chores por mim, Argetina. Não me deixes, fica comigo). The same question about why she would switch, as I asked about the Spanish version pertains here. Also, even if a switch is necessary for a reason I'm missing, why is tu used instead of você? Is there a region in Brazil in which tu is used and actually conjugated differently than você? I lived in Belém-do-Pará and people would say não te vi faz muito tempo, etc, but I always heard sentences like tu tem que vir comigo, never tu tens que vir comigo. If the use of tu is to create a kind of archaic effect, why isn't vós used in place of vocês in the rest of the song?

( Lyrics and video is below the cut. Any help is appreciated.Collapse )