Standing for the Aseret haDibrot (Ten Commandments)

Hi,

One who is in a synagogue where they stand for the Torah reading of the Aseret haDibrot is obligated to stand, even if his personal custom is not to stand.

(Rav Moshe Feinstein, Igrot Moshe Orach Chaim 4:22)

Have a great day,
Mordechai