The person in charge of the emergency stop button on the Dreamworld ride that killed four people was an 18-year-old on her first day on the job.
However it is also understood the water levels on the ride were lower than normal and a sensor should have triggered an emergency stop but didn't.
Two men and two women died on the River Rapids ride on Tuesday when a raft flipped over. Two children survived the accident.
The 18-year-old is understood to have gone through introductory training for the role and was tasked with manning the emergency stop button for a number of hours.
It is standard practice that staff rotate through several duties per day and spend a number of hours in each role.
Dreamworld says the park will reopen on Friday for a memorial day, with entry proceeds going to the Australian Red Cross.
Dreamworld management is adamant the ride was safe, saying in the statement the Thunder River Rapids ride passed its annual mechanical and structural safety engineering inspection last month.