Conversation so far:
What did Irving Thalberg do at Universal Studios?
Irving Thalberg found work as an office secretary at Universal Pictures' New York office.
What did Irving Thalberg do at Universal Studios next, after working as secretary?
Irving Thalberg later became personal secretary to the studio's founder and president, Carl Laemmle.
Did Irving Thalberg do anything else besides work as secretary and personal secretary to Universal Studios' president?
Carl Laemmle told Irving Thalberg to take charge as studio manager, overseeing day-to-day operations.
Where else did Irving Thalberg work as studio manager?
Irving Thalberg worked as studio manager at the Los Angeles studio.
Did Irving Thalberg work anywhere else besides the Los Angeles studio?
No
What did Irving Thalberg have to do in Los Angeles?
At age 20, Irving Thalberg became responsible for immediately overseeing the nine ongoing film productions and nearly thirty scenarios then under development.

Question: How did he get the job so young?
Self-contained rewrite: How did Irving Thalberg get the studio manager job so young?