Onana says he will 'shine' at Manchester United after battling early struggles
The Cameroon international joined the club from Inter Milan in July in a £47.2 million deal but a string of costly errors put him under huge pressure.
Onana said it had been tough to adjust to life in Britain.
"It took me six months or seven months not to play good, just to feel good," he said.
"It was a difficult time for me. Now I'm feeling a bit better because everything was new. It was difficult for me to feel at home because of so many reasons, a new country.
"But now I'm feeling good. I don't want to talk about my performance because I know the goalkeeper I am and I have done much more than what I just did.
"So, for me, the most important thing is to be set, to be happy and I will shine."
Onana spoke openly about his challenging start to life in Britain ahead of United's match against Premier League champions Manchester City on Sunday.
The goalkeeper's errors during United's short-lived Champions League campaign were costly but his performances have since improved markedly and he believes he is now on an upward curve.
"I think I had a turning point, but not on the pitch because, like I said, more mental because everything was different," he said.
"Of course, I moved last season from Amsterdam to Milan, but that adaptation was quite easy.
"But it took me seven, eight months here. It was just time to learn and just go game by game. I hope we will end on top."
Onana said he had received support from his teammates as soon as he arrived at Old Trafford.
"They always believed in me, they told me from the beginning, 'Andre, listen, the quality is there, it's just a matter of time,' he said.
"I am very happy, especially with the supporters, the fans. They were nice with me even in difficult periods and I'm very thankful. I can only thank them.
"I think everything is behind me. Now we have to move on and I think together a great time will come."