>Season 1
Showrunner: Daron Nefcy
Head Director: Dave Wasson
Story Editor: Jordana Arkin
Staff Writers: Nate Federman, Mike Yank, Noelle Koenig, Emily Brundige
Episode Directors: Aaron Hammersley, Mike Mullen, Piero Piluso

>Season 2
Showrunner: Daron Nefcy
Head Directors: Aaron Hammersley & Dominic Bisignano
Story Editor: John Infantino
Staff Writer: Amy Higgins
Episode Directors: Aaron & Dominic (on a ton of eps boarded by freelancers, roughly a 3rd of the season), Giancarlo Volpe (Evon/Le Tang eps, Sabrina/Amelia eps), Piero Piluso (Gina/John eps, Zach/Brett eps)

>Season 3
Showrunner: Daron Nefcy
Head Directors: Aaron Hammersley & Dominic Bisignano
Story Editor: John Infantino
Staff Writers: Amy Higgins, Bryan Caselli
Episode Directors: Aaron & Dominic (Zach/Cassie eps, Kristen/Jushtin eps), Tyler Chen (Sabrina/Amelia eps, Gina/Sarah eps), Brett Varon (Madeleine/Nicolette eps, Casey/Charlotte eps)

>Season 4
Showrunner: Daron Nefcy
Head Directors: Aaron Hammersley & Dominic Bisignano
Story Editor: John Infantino
Staff Writers: Amy Higgins, Todd Casey
Storyboard Supervisor: Tyler Chen
Episode Directors: Dominic Bisignano (Kristen/Amelia eps), Sabrina Cotugno (Gina/Cassie eps, Madeleine/Nicolette -> Madeleine/Ariel eps), Brett Varon (Zach/Kenny -> Kenny/Matt eps, Casey/Charlotte eps)

Notice how the main crew on season 4 is relatively unchanged from the season 2 crew (biggest change being the non-head directors, who only influence eps they direct)