Rooney was desperate to leave Old Trafford this summer, only to be thwarted by the club's refusal to sell him to a Premier League rival, with Arsenal and Chelsea the two clubs to show firm interest.
The England striker has started the season in fine form, scoring five goals in eight games, but although he says he has felt "happy" and "settled" for months he also told of his irritation at not being played up front alongside Robin van Persie.
"Everyone at the club knew where I wanted to play, and I think that's why I was disappointed," Rooney told reporters. "I got told to play in midfield, and I didn't want to. I just think there had to come a point when, for my own career, I had to be a bit selfish really.
"I actually felt when I played in midfield I did OK, but I didn't want to play there. I've had no problem in the past playing out of position, but I felt I deserved the right to play in my position and that wasn't happening.
"I think, naturally, I was a bit disappointed and maybe that affected some of the games I played. I know myself that last year wasn't my best season but there were times when I was playing in different positions. I didn't feel I got a consistent run of games up front. Sometimes when you're not playing in one position all the time it's difficult to adapt."
Despite talking publicly about some of the reasons for his unhappiness at United over the last few months, the 27-year-old also claimed that he never, in fact, had any problems during the transfer window.
"To be honest, I've been settled all summer," Rooney said. "I really have been happy all summer. From the outside looking in, it might not have seemed like it, but I have been settled.
"My wife had a new child and I'm just delighted to be back playing and injury-free. I've got my head down and worked hard. I've been focused, and I've been wanting to prove to people that I am a top player. That's what I've really tried to do."
Manchester United rejected two bids for Rooney from Chelsea during preseason, before Jose Mourinho urged the striker to make his intentions known during the final week of the transfer window.
Rooney decided to remain silent, publicly at least, as he quickly realized that the Red Devils were not interested in a sale.
"I'm sure the club made that clear," Rooney said. "Obviously there's been a lot of stuff happening and everyone has been waiting for me to say something, but I've spoken to the people who matter at the club and we've known ourselves what was going on.
"I didn't want to come out saying anything. I just wanted to concentrate on my football. That's what I've done and that's what I'll continue to do. I'm not going to go around saying: 'I wanted to stay' or 'I wanted to leave.' I'll concentrate on my football and see what happens after that."
It is not the first time Rooney, whose contract expires at the end of next season, has used that line to divert awkward questions about his current situation. When asked by ITV if he would be signing a new contract at Old Trafford following a Champions League match in September, the striker flatly stated that he is concentrating on his football. He employed a similar tactic again in Wednesday's press conference.
"You can see I'm playing and I'm happy in my football. I'll have more discussions with the club and we'll see what happens from there."
Reports at the beginning of the season suggested that Van Persie was unhappy with the playing tactics and high-intensity training implemened by Ferguson's replacement, David Moyes, but Rooney, for one, says he is enjoying life under his former Everton mentor, including the extra workload.
"It's a bit different in terms of David Moyes and his staff coming in," Rooney said. "The training is different, there's a different style, a different way of thinking about how he wants us to play. Honestly, the training has been so hard. We've done a lot more running. Long running, quicker running, sharper running.
"I feel that's really benefited me. I feel as fit as I ever have done. I had a couple of injuries pre-season but I feel great and in good shape. It's a mixture of things, but I am happy and I am enjoying my football."