Here, from a parish website, is the answer.
For the Pater noster (Our Father) the preferred position is with palms held together or hands folded. Hands should not be extended outwardly or upwardly; this position is reserved for clergy.
There is much more on the link but the upraised hands thing gets to me. In my own Church people are doing it when the Priest says “peace be with you” and they reply with upraised hands “and with your spirit”
It is starting to have a pentecostal feeling to the masses.