United failed to win a trophy last season, after losing out to local rivals Manchester City in the race for the Premier League title.
“I think we’ve all learned a lot,” said Rooney.
“There have been a lot of games where you get a feeling afterwards that you never want to have again. Hopefully we can get hold of that feeling and make sure it doesn’t happen again.
“Just look at all the young players in the squad: they’ve played a lot of games, had a lot of ups and downs and most of them are already getting selected for their national teams.
“That’s all going to help them. The next two or three years will be a big test for them and I’m sure we’ll all pull through it.”