Mainoo had his best performance under Amorim against FCSB in the Europa League, scoring a goal and assisting another in the 2-0 victory.
Playing in a No.10 role, Mainoo excelled with the freedom it provided, linking well with Bruno Fernandes and Alejandro Garnacho.
"The Kobbie position today, we need time to understand the players, he was struggling a lot defending as a midfielder," he stated.
"Now more as a ten you can feel that he was so free, playing the ball near the box is really good, the small connections. We need time to work with the players and understand the best positions for them."
United always had control of the game in the National Arena and in the second half they upped the tempo to score twice, while wasting opportunities to add to that advantage.
"We controlled the game quite well, in the beginning a bit more slowly with the tempo but the opponent was really close, they covered all the space and sprint a lot and try to press our three defenders with one player," added Amorim.
"We managed to create some chances, in the second half you can see the opponent getting tired, more slower, we had more space between the lines with Kobbie, one-vs-one with Amad and the pace of Garna helped a lot. We scored two, should score more, had transitions sometimes four to two. A good game, we needed some rotation and now the focus is on the next game."