Saying that you are told to do something, you're implying that a particular behaviour is expected from you in a particular situation on a regular basis, eg:
I am told to wash my hands before meals
roughly speaking means that you are expected to wash your hands before every single meal you have.
I have been told to do something merely expresses a suggestion or an order from someone else in a particular situation, eg:
I have been told to wash my hands before meals (in the recent past, someone told you to wash your hands before meals; of course, such a suggestion or order could also cause you to wash your hands before meals from that particular time onwards, on a regular basis.
- For Teachers