The 22-year-old, described by manager Louis van Gaal as having the "potential to become a great footballer", has scored six goals in all competitions for United and two in the Premier League all season.
"I haven't yet lived up to everything people expected of me," Memphis told British media.
"I have a lot of expectations of myself, and it will come -- confidence and experience will help. You have to learn from your mistakes and keep working hard to improve."
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The winger said he was working closely with former midfielder and United assistant manager Ryan Giggs in a bid to find consistency and eliminate the mistakes that have dogged his campaign.
"Ryan Giggs is a legend, he talks a lot with me, he gives me advice, he has experienced everything already so he can help me with lots of things," Memphis added.
"He works a lot with me and he and Wayne Rooney give me lots to think about. That really inspires me because they are legends, I feel that I am doing something well with them."
(Reporting by Simon Jennings in Bengaluru; editing by Sudipto Ganguly)
