The 16 year-old Belgian joined United last year from PSV Eindhoven and made his U18 debut for the club late, last season.
"You must have confidence and ambition," he said. "At United, you see the guys every day that you dream about. The first time at training I was on the field next to Paul Scholes. I froze for a moment. But now I know better.
"At Manchester, there's a real family atmosphere."
Pereira had to play much of the season in friendly action due to registration difficulties.
He added: "Was I annoyed about that? Nope, PSV did not want to help, so my papers were submitted too late."