Security features on Australia's Notes

RBA: Security Features on Australia's Notes:

"The Bank made the move to polymer to make Australia's notes more secure against counterfeiting. Polymer notes are also more durable than paper notes (lasting around four times as long), are cleaner and more hygienic, and can be recycled at the end of their useful life into a range of plastic products."

We had our first polymer 10 dollar note in 1988 because it was the 10 dollar paper note forgeries which had been the bane of our existence. The new note co incided with the bicentennial celebrations . The bank site above lists why it is supposed to be difficult to counterfeit and there is a video on the same site. This is what we were told. We developed the polymer note technology so I am really disappointed it has allowed 15 billion dollars worth of forgeries which we had no idea about. Everyone knew about the 10 dollar paper note so we were onto it all the time. We have not been told about these forgereies. What are they and where are they and how does it happen?