There really is no theological point involved. There is not an official translation anywhere. There is no text in the Enchiridion of Indulgences. Some prayer books use you and your while others use thee, thy, and thou. It is a matter of personal preference and generational differences, what sounds best to a person’s ear and what he or she memorized as a child.
When it comes to the Lord’s Prayer, the Sacramentary uses thy in the first part of the prayer. Our bishops thought that was the way people learned the prayer and they would be most familiar and comfortable with it. Yet in the priest’s part and in the doxology following the prayer, the Sacramentary uses you and your to address the Father.
The biggest reason for using one over the other (thee or you) is for unity in public and common prayer.