Speaking to audience members at “The Daily Show” on Thursday evening, Trevor Noah explained that, though the program they were about to see would not be broadcast, it was still crucially important.

“Welcome to ‘The Daily Test Show,’ ” he said excitedly. “This is where we’re testing if this ‘Daily Show’ thing is a good idea or not. So, the fate of the universe is in your hands, people.”

While existence will continue either way, the stakes could hardly be higher for Mr. Noah, 31, the South African stand-up chosen by Comedy Central to succeed Jon Stewart as host of this parody news program.

After Thursday’s test show, the fourth and final run-through that Mr. Noah and his “Daily Show” team produced in a two-week period, he makes his debut on Monday night.

This new “Daily Show” will be a substantially different program, based simply on the man now sitting in its anchor’s chair.

And yet, to gauge from this taping and the preparations that preceded it, “The Daily Show” has hardly changed at all. It features a new set, subtracting the familiar globe that hung over Mr. Stewart’s head while adding an elegant, expansive desk.

There is still an opening act in which Mr. Noah lampoons the events of the day (in Thursday’s case, Pope Francis’ visit to the United States); in-studio and field segments featuring “Daily Show” correspondents; and interviews with cultural and political figures, like the test evening’s guest, the CNN host Fareed Zakaria.

Even the familiar opening theme, composed by the rock musician Bob Mould, is sticking around for the time being.

But the program’s success or failure rests largely on the comedic chops of a performer who, despite his international reputation, is still learning how to fine-tune his act for an American audience.

As Mr. Noah explained at Thursday’s show, his goal is to optimize his jokes so that “no matter where you are, they cross borders, like Syrian refugees — and then get them accepted in more places than Syrian refugees.”

And on opening night, he will be playing not just to the modest capacity of this Midtown Manhattan studio, but also to millions of people measuring him against Mr. Stewart, the outspoken and influential satirist who led “The Daily Show” for 16 years.

Acknowledging this uneasiness at the test show, Mr. Noah described Mr. Stewart as “our political dad,” adding: “It’s weird because Dad has left. Now it feels like the family has a new stepdad. And he’s black.”

When Mr. Noah entered the office at 9:15 a.m. that morning, dressed in a Nike T-shirt and G-Star jeans, for his first meeting of the day, the room was already filled, largely with veteran “Daily Show” writers and producers who had worked with Mr. Stewart.

The new host kept mostly quiet while his colleagues riffed on video footage of Pope Francis stopping his motorcade to greet a child who had broken through a security barricade, and of Donald J. Trump telling his supporters that, unlike the pope, he didn’t believe in global warming.

But Mr. Noah was more assertive in a later, smaller meeting with his executive producers as they reviewed scripts for the test program.

He wanted to reshape a segment in which he and the correspondent Jordan Klepper discussed the pope’s travels in America, to emphasize that this news was overshadowing the also momentous visit to the United States by President Xi Jinping of China.

“We’re commenting on the fact that everyone is only covering the pope,” Mr. Noah explained. “Everyone’s going mad over the pope. What I found interesting is the fact that the Chinese president is there, and no one’s talking about it.”

Steve Bodow, a longtime executive producer for “The Daily Show,” agreed with Mr. Noah’s point. “The pope is the Donald Trump of international relations,” he joked.

Mr. Noah also gave pointers to one of his new correspondents, Ronny Chieng, who would be featured in a sketch where he reluctantly reports news for children, called “Ronny’s Cutie-Patootie News Cabootie.”

“Don’t be afraid to change it to your style of speaking,” Mr. Noah told him. “All those little bits between you and I, don’t worry about it — switch it up, the way you’d normally sound.”

These segments appeared to reflect Mr. Noah’s notes and suggestions when they were performed at the test show that evening. And he scored a few laughs in what could have been an airless interview with Mr. Zakaria, who has appeared on “The Daily Show” 19 times.

“Yes or no,” Mr. Noah asked, “do you think Bernie Sanders stands a chance?”

Mr. Zakaria started to give a verbose reply when Mr. Noah cheekily interrupted him. “It was a one-word answer,” he said to laughter.

Despite these preliminary successes, Mr. Noah recognized the significant amount of work that lay ahead for him.

As he said of his new job on Thursday evening, “The most challenging thing is trying to make it look like it’s easy.” He added: “You get into it, and you think, ‘Oh, no, this is doable.’ I just watch some TV, and then I’m like, ‘Ha, ha — joke.’ It’s a lot harder than that.”

“The most surprising part,” he said, “is that Jon Stewart does not look like he’s 175.”