The AudioBox USB is just an interface. There is very little you can adjust on the AudioBox itself to change the sound of the recordings. All effects processing and other manipulation of the audio would be handled within your recording software.
However if the raw recording of your guitar isn't to your liking then no amount of DAW-magic will make much of a difference.
In my personal experience I find that plugging an acoustic guitar directly in to an interface is not going to sound good, especially in the manner you're describing. Your best bet to recording a good sounding acoustic guitar would be to point a microphone at it.
A quick Google search for "How to mic a steel guitar" will give you some great jumping off points and ideas for types of mics to look in to.