Defender Tyler Fredricson, who is 20 years old, will now wear the number 33 shirt, instead of the number 55. Striker Chido Obi, who is also 20, will wear the number 32 shirt, having previously worn the number 56.
Both players gained experience by playing in the first team last season.
Fredricson made his Premier League debut against Wolverhampton Wanderers, and also started a match away at Brentford.
Meanwhile, Obi made his debut at Tottenham Hotspur in February.
