Can someone explain (sorry, very basic question)

[SamG]

Just a fan, not a coach, parent (of a football player), or official.

Offense breaks huddle and goes to the line. They look like they're set, then, almost as 1, multiple players (sometimes linemen?), stand up and look to the sideline to see if the coach wants to audible. How is this not a false start?

Also, watching Sugar Bowl last night... Louisville on offense, breaks huddle, gets to the line, appears to be set, then multiple players would shift, everyone sets again, and they hike. How is this not a false start or too many in motion?

I'm sure my understanding of the rule is not right, but hoping someone can set me straight.

thanks