Dear Yvonne,

The actual text of liturgical prayers cannot be changed, not even a little bit, unless there is explicit permission within the instruction for the prayer.  The Gloria does NOT contain such permission, and therefore the text must be used exactly as written.

Now, that doesn't mean that composers aren't allowed to use thier creativity to embellish and beautify thier work by repeating phrases.  Oh and technically...  any time a human voice sings.. well then it becomes a song... and there is nothing wrong with praying in song!  What is important is that the "song" or "prayer" does not become too popular or common...  Sacred, by definition, means that something (for example sacred song) is set apart from the ordinary, and set apart usually for religious purposes.  This is why we don't allow Rock music at our liturgies.. because Rock certainly is not "set apart" from our secular culture!

Back to your question about the wording, as I said, the text cannot be changed at all.  This comes directly from Vatican II:

22. 1. Regulation of the sacred liturgy depends solely on the authority of the Church,
that is, on the Apostolic See and, as laws may determine, on the bishop.

2. In virtue of power conceded by the law, the regulation of the liturgy within certain
defined limits belongs also to various kinds of competent territorial bodies of bishops
legitimately established.

3. Therefore no other person, even if he be a priest, may add, remove, or change
anything in the liturgy on his own authority. (Sacrosanctum Concilium)

So what to do then if the choir is singing inappropriate music?  Well I think in most parishes the music is selected by a music director or choir director and NOT the priest personally.  Many times the parish bulletin publishes phone numbers for the parish staff.   You certainly may give the director a call or visit with him/her after Mass.. Just make sure you do this with charity!

Mr. Slavek