You don't change this setting from the internet services but by entering the config at the devices touchscreen.
Logon as admin, press the machine status button, move to the Tools tab, Service Settings, Embedded fax.
From there on, you'll find someting like outgoing faxes default (here it's in Dutch, so I don't know the exact English translation), where you'll find the fax confirmation setting. By default it's set that it only prints a confirmation sheet upon failure.
Could be a firmware bug. I suggest that you install the last version. If you have it already loaded, you should contact the local support centre to get a more recent one.
I am now working with a Workcentre 7545. I am trying to change the settings so that it will print a fax confirmation everytime. I login and change the setting and save it but everytime I get a message that says when I logout the changes will be lost.
I changed the setting on the machine thru the internet interface but that still didn't do it.