"We've got the be careful and get the balance right when transitioning these new boys into the team," Cooper said.
"We learned last year it takes time. That's gong to be the challenge, but it's an exciting one and it's one that we want.
"As a coaching team, we'd rather have decisions to make all over the pitch than not.
"Lots to digest from the game - some good bits, but some bits where we know it wasn't quite right. A lot of that that might be the newness of the shape and some players coming in. That's OK.
"We needed high width in the game and speed - with Anthony [Elanga] and Callum [Hudson-Odoi] we obviously have that. In other games we might not think that's where the space is. What we do have now in the squad is options to have a variety in our plan."
Did you know?
Nottingham Forest have lost just two of their past 17 home Premier League games (W8 D7) and are unbeaten in five at The City Ground.
Taiwo Awoniyi has either scored (nine) or assisted (two) in his past nine Premier League appearances for Forest.
Hudson-Odoi became the first player to score on his Reds Premier League debut since Geoff Thomas in August 1998.