There is no way to save them, a Feature request (many of them) have already been done.
It's a security issue, anyone who walks up to the printer gets access to what could be someones personal files.
So hopefully they will figure out how to save usernames in a selectable format, then you would just need to type the password, or a PIN
Thank you for the information. Due to changes with Dropbox, the Print and Scan for Dropbox App will be temporarily unavailable. An announcement will be posted in the forum when the Print and Scan for Dropbox App is available to use again. Please check the forum over the next several days. Thank you