Dear Shanny,
The worldwide norm is this: “Unless other provision is made, at every Mass the people should stand from the beginning of the entrace song or when the priest enters until the end of the openin gprayer or colect; for the singing of the “Alleluia” before the Gospell; while the Gospel is being proclaimed; during the profession of faith and the general intercessions; from the prayer of the gifts to the end of the Mass, except at the places indicated… (GIRM 21).”
The American usage is identical except the period from after the “Sanctus” to after the Great Amen, where additional kneeling is madated.
Go where you are best able to enter into the Sacred Mysteries.
Fr. Vincent Serpa, O.P.