United produced an impressive comeback at Deepdale after Scott Laird put the hosts ahead just after the break, and eventually saw off the League One side thanks to goals from Ander Herrera, Marouane Fellaini and Wayne Rooney.
Young replaced Radamel Falcao on the hour mark as the Reds looked for an equaliser - a change which inspired Louis van Gaal's side - and the midfielder praised the determination of the players after the game.
“We showed that fighting spirit that we’ve always had throughout the years," he told MUTV. "We went a goal down, but got ourselves back into the game.
"It was disappointing [to go behind] with all the possession we’d had. We had to fight back, we said before the game that we wanted to get through to the quarter-final and we’ve done that so we’re delighted.
“The manager said he wanted to change things when I came on. Any system he wants to play, we’re all out there to do a job and we’ve got many players who can play in a number of formations."
The Reds drew level through Herrera shortly after Young joined the action, before going on to seal a home tie against Arsenal in the next round. Young lauded the United goalscorers
