This article details step by step, the process of replacing a products Deliver File purchase action:
1- Choose Products from the left menu of your DPD dashboard.
2- Hover your cursor over the product you'd like to edit and choose Actions from the menu that appears.
3- Find the Deliver File purchase Action you'd like to replace and choose the Action Options dropdown menu on the right, then Settings from that menu.
4- Now just click the Select File to Upload button (or the FTP option if you're using FTP to upload your files), choose a file, upload it to replace the old file, then click the save button and you're done.