Just under 8 million people watched Sunday’s season premiere of “60 Minutes,” down 21 percent from last year. Viewership for the N.F.L. lead-in fell by about the same.

After a chaotic off-season, “60 Minutes” returned to CBS with a revamped show and an exclusive interview with an Air Force pilot shot down over Iran. The Nielsen number — 7.9 million viewers, down from 10 million last year — is a disquieting result for Bari Weiss, CBS’s editor in chief, whose overhaul of “60 Minutes” has become an early test of her tenure.

Ms. Weiss purged senior leadership, fired several correspondents and installed a new executive producer, Nick Bilton. Critics attributed the decline to her decision-making, but ratings depend on many factors, including N.F.L. matchups. CBS and Fox both aired late-afternoon games this past Sunday, contributing to a drop in CBS’s football viewership.

CBS News said it was “so proud of the exceptional journalism” in the premiere. “60 Minutes” remains the most popular news program on television, averaging 9.1 million viewers an episode last season.