Using Second Copy 7, you can set the profile to copy files to a removable USB drive based on its volume name, and not based on its drive letter.
Go into the profiles' properties and select "Where?" tab for the Destination folder (where you have specified the usb drive letter - make sure that the USB drive letter is valid). Enter the drive letter and the path for the usb drive where you want to copy files (e.g. "E:\Backup" without the quotes). Then check the box "Copy only to Volume named" box. Then go to the Finish tab and click on the Finish button to save the profile.
Then go back to the profiles' properties, and now this time enter "?:\" in the Destination folder filed instead of the actual drive letter (e.g. "?:\Backup" without the quotes). Then go to the Finish tab and click on the
Finish button to save the profile. From now on, Second Copy would automatically detect the correct drive letter based on the USB drive's volume name.
"Copy only to volume named" option box is only displayed if Windows reports the drive to be a removable drive. Even though your drive may be removable Windows may not be reporting it to be a removable drive. (Just to see how the option would look, enter A:\ on the destination folder field.)
If the above option box is not displayed in your case, then first set a hidden option called "AlwaysShowVolumeNames=1" in the profiles.dat file. For more information on setting this option, please refer to the Help file and look under Hidden Options topic.