22-year-old Sims left on a loan deal this summer that surprised many.
And he has explained the connection between New York and Ralph Hasenhuttl's former club RB Leipzig played a part in the move.
"On paper, it seems a bit of a weird one but there was thought behind it," revealed the Saints academy star to reporters.
"Southampton are very good. They watch all the games, they ask me how I'm getting on during the week. I'm not just sort of out of sight, out of mind.
"That's a big thing as well because I'm still a Southampton player so I don't want to be forgotten about. I don't feel forgotten about."