France World Cup winner Raphael Varane arrived from Real Madrid to bolster the centre of United's defence, while England forward Jadon Sancho was lured from Borussia Dortmund.
United have yet to string together a consistent run despite their influx of top-class talent.
Portugal star Ronaldo believes it is a matter of allowing the team time to gel.
"We are in a moment in my opinion that Manchester do a few changes. They buy me, they buy Varane and Sancho," Ronaldo told Sky Sports.
"The adaptation will take time, even the system of the game that we play, but I think step by step we have to put it in our mind that everything is possible.
"Everyone should know their role. I know my role in the team, in the club, my role is to score goals, to help the team with my experience and knowhow to understand the game.
"If everyone is thinking like that, sacrifice for the team, I think we will be a better team."
United have gone three Premier League matches without a win, a run that included losses to Leicester and Aston Villa.
They were in danger of another damaging loss in the Champions League on Wednesday when Atalanta raced into a two-goal lead at Old Trafford.
But United eased the pressure on Solskjaer with a spirited second-half fightback capped by Ronaldo's late headed winner.
Solskjaer's side have no margin for error this weekend when they host bitter rivals Liverpool, who are already four points ahead of them in the Premier League.
It is the kind of high-stakes encounter that United brought Ronaldo back to Manchester for.
Criticised for his work-rate in some quarters, as well as his grumpy response to being named as a substitute for the draw against Everton, Ronaldo has blocked out the noise to net six goals in eight games.
He insists there is no chance he will be unsettled by the relentless scrutiny United are under.
"I will close mouths and win things. Criticism is always part of the business," he said.
"I'm not worried about that. And I see it as a good thing to be honest.
"If they worry about me or they speak about me, it's because they know my potential and value in football still."