Moyes was one of several managerial changes in the Barclays Premier League this summer but feels he landed the best role of them all.
And he says he was always fully aware of the task ahead when he opted to end his 11-year tenure at Everton to join United in the close season.
"I knew the enormity of the job at Manchester United – that hasn't changed for me at all," the Scot said at his press conference on Tuesday. "It's the biggest job and for me personally it's a great challenge."
Moyes is confident that another arrival from Everton, midfielder Marouane Fellaini, will fulfil his potential as he settles in at Old Trafford this season.
"I think Marouane's probably going through the same settling-in process as most players who join Manchester United go through," Moyes said.
"I don't think it's just Marouane or David Moyes; I think it's players who join this club.
"There are some players who hit the ground running and can go straight in. But then there are others for whom it takes quite a bit to settle in and there have been a few here."
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