The Spanish champion has failed to win any of its past six competitive matches on its travels in a run stretching back to May, conceding 11 goals and scoring four.
Barca was somewhat fortunate to escape with a goalless draw against Borussia Dortmund in the UEFA Champions League in midweek, having already lost to Athletic Bilbao and drawn with Osasuna in LaLiga.
Granada is up next for Valverde's men and the 55-year-old has demanded an improvement from his players.
"When we are away from home, our level of effectiveness and possession decreases," he said.
"It is costing us in that we are not getting the results we expect when playing away.
"Everything we have been doing well at home we forget to do away. We want to change this. We must be more forceful and decisive."
Lionel Messi made his first appearance of the season from the bench in Wednesday's (AEST) stalemate with Dortmund and is in line to start against Granada, which is level on points with Barcelona after making a positive start to the campaign.
"Messi played well against Dortmund, despite having been out for a while," Valverde said. "We hope that as he gets more minutes. He gives us a lot - like he always has.
"His presence changes things in the attack. We will see who will play against Granada."
Ansu Fati has scored two LaLiga goals in three appearances and became the youngest player to feature for Barcelona in the UEFA Champions League after being named among its starers against Dortmund.
But Messi's return could see Fati drop down to the bench, while Ousmane Dembele is also closing in on a comeback after taking part in training this week.
Asked if Dembele is now behind Fati in the pecking order, Valverde said: "We will see if he has taken his place.
"So far they have not trained together. There is competition in the team and it will stay that way. It is a matter we will answer over time."