The Belgian spent much of his first season at Old Trafford as a defensive midfielder.
Van Gaal has used the former Everton star as a No. 10 at times last season.
Van Gaal said in a news conference: “He can play in a No. 9 position and a No. 10. He can also play [as a No.] 6 [a holding midfielder] and [a No.] 8 [a box-to-box midfielder] but this year he shall play more 9 and 10 than 6 and 8 because there we have other players.”
Fellaini added: “In the past I played No. 10 and No. 9 sometimes so I can play there and help my teammates and my team.
“It is not important where I play. It is important to win the game. Of course it is different to play midfield and striker but I enjoy all the positions I can play.”