Robert Wagstaff killed himself in January 2017, just weeks after his 18th birthday.
A fatal accident inquiry at Falkirk Sheriff Court heard that staff at Polmont - where he had been for two months - had failed to read a report which warned them off his poor mental state and recognise him as a suicide risk.
It noted that he had tried to kill himself before.
The inquiry heard that Jeffrey Richardson, a community placement officer for Polmont, had been sent the report but did not read it or share it.
Sheriff John Munday, in his written determination, noted: "I have concluded that it is likely, had [Mr Richardson] read the transition report, and appreciated the significance of the information in it, then he would have recorded this information on the system."
Robert Wagstaff, from Paisley, arrived at Polmont from a secure unit, St Mary's Kenmure, in Bishopriggs, in November 2016.
He had admitted committing an assault to permanently disfigure and was transferred to Polmont.
He was initially kept in segregation before being moved to mainstream accommodation.
Sheriff Munday added: "Had the information been made available, appreciated and disseminated then there ought to have been an immediate concern.
"It would have been likely in those circumstances that those dealing with Robert would have considered the application of the suicide prevention strategy which could have resulted in measures being taken to secure his safety."
A series of recommendations for refresher training within the Scottish Prison Service was urged.
A spokesperson for the service said: "The safety and well-being of everyone in our care continues to be a priority."