Ten Rouwelaar has arrived to replace Richard Hartis and Onana said, "It’s very good, to be honest.
"I also had a very good relationship with Richard, he was a really good guy and helped us a lot, especially when I came here and faced difficulties. He was there for me, so I thank him for all what he did for me and I think all the goalkeepers were very happy with him.
"Now the club decide to move on and bring someone else and we are working together and we are happy to work with Jelle.
"He has his own way to work. It’s nice, we are having fun and enjoying it, and the most important thing is for the team to win. So we are ready to face anyone."
Onana also said: "As the best club in the country, the perspective is always high.
"It’s to win everything, fight for every single game and be more consistent. We already showed in the past games we can beat anyone so we’re going to fight to win everything.
"It’s important for us. We know what we represent, we represent a huge badge. It’s not easy playing for Manchester United because the expectation is always higher.
"I don’t think it was good enough last season because I’m coming from playing in the Champions League final and the FA Cup is important but not enough for Manchester United.
"The targets have to be really high and we will go for it this season. We are working very hard, being really positive. I'm really excited about the new signings. I think the way my teammates are working hard every day, I’m very positive."