Retail theft youth record sealed?

A week ago I was caught stealing 30 dollars worth of merchandise and I'm 17 until june 25th. I want to know if once I pay the fine and turn 18 will my youth record be sealed? The cop said that to have my record expunged I would have to complete a youth advisory program. Is that the same thing as probation and just not doing anything illegal? Also, is getting my record sealed and expunged the same thing?