Have an auditor talk to them and ask them questions about the transactions. Might wake them up a bit. & tellers don't know the difference between an auditor and an examiner.
I've had auditors do this for me ... works pretty well. Helps them take it a little more seriously.
If that doesn't work - you're going to need support from senior management.
Also, you could try the tactic that, if they don't ask questions, that means you may have to file a SAR, if you file too many SARs, you'll make them have the "sorry customer I'm closing your account" conversation. That usually motivates branch managers/supervisors to get their tellers to pay attention.
My opinions are my own, and not that of my employer.