This page has a video guide on how to update your newspaper barcodes from Retailer's self-generated barcodes to the proper barcode in Retailer.
For new users who have been using Retailer for a short period of time, updating barcodes with this method is perfect.
However, if you are from a store who has had Retailer for a long time, or you've taken over a store that has our software for a long time, you should change the barcodes via the Change / Merge Barcodes in the utilities menu outside business hours. This is because changing the barcodes for all of the sales history can take a long time and can lock your POS terminals up.