meteor1 :
I bought a new Galaxy S4 at a Navy Exchange store. When I go to the "set up/change password", it asks me to type in the 'old' password. I have never entered a password for this device. Is there a default password for new Galaxy S4s that I need to enter as the 'old' password?
You may be attempting to setup the password on the SIM card itself. If that is the case, the default is usually 0000. This will protect the SIM card's contents and the password will be needed if the SIM is transferred to another phone, but will not protect the phone itself.
To setup a password for the phone itself, follow this:
Settings -> My Device -> Lock Screen -> Screen Lock
Select either PIN (numeric) or Password (alphabetical)