Flick is hopeful midfielder Frenkie de Jong can return as Barca look to bounce back after suffering two losses in 10 days, against Monaco in the Champions League and Osasuna in LaLiga.
The German manager has been navigating an injury crisis, with Dani Olmo, Ronald Araujo, Gavi and goalkeeper Marc-Andre ter Stegen among the players sidelined.
He benched regulars Lamine Yamal and Raphinha in Saturday's 4-2 defeat at Osasuna keeping the Champions League clash in mind.
Dutchman De Jong has not played since April due to an ankle injury and the 27-year-old missed the European Championship because of his recovery.
"We will play with the team we believe to be the best in order to beat Young Boys. The first game (at Monaco) we lost, yes. But we must not be depressed," Flick told reporters.
"We have to recover our balance after the defeat at Osasuna. We have to build the game with fewer mistakes. Responsibilities must be assumed.
"We need fresh legs and Frenkie's return is great news. Even if it's just for five or 10 minutes. If he gets the chance, he'll play."
Flick previously said his choice to rest key starters affected the team in their first domestic loss of the season at Osasuna, ending a seven-game winning streak.
Young Boys will arrive in Spain following a 3-0 defeat by Aston Villa in their opening Champions League match at home.
Asked if the five-times European Cup winners have lost respect after their defeat at Monaco, Flick said: "I am positive we can win... we play good football - entertaining football. And if we need to gain the respect of our opponents once again, we're going to work hard on that."
Flick added he is in contact with Polish goalkeeper Wojciech Szczesny, who has reportedly agreed to come out of retirement to help Barca following first-choice Marc-Andre ter Stegen's season-ending injury.
"Yes, I spoke with him, but I'm not going to say anything more. If he signs for Barca in the next few days at the next press conference we can talk about the issue, but not now."
Barcelona have been banned from selling tickets to their fans for their next Champions League away game, at Red Star Belgrade on November 6th, after their supporters were found guilty of racist behaviour during their match against Monaco.