There are some lessons in my (Lisa McCormick) Guitar Fundamentals Course on improving your tone. (or you aim, or your angles, so that all the fingers can fit onto the fingerboard to make the chords you are going for). 

For the most part, it comes down to nuances in how your fingers are making contact with the strings - some of which may be tough to detect when you are brand new to the instrument!

But as your hand, and your ears, continue to get attuned to the guitar, you may find that with a bit of investigation as to WHY a note in a chord is sounding muffled (for instance), you can then try tweaking your positioning just a bit, this way or that, to clear it up. 

Also, always make sure your left hand fingernails are good and short, so they ae not getting in the way of your fingertip making good direct contact with the string and the fingerboard. 

Have fun! - Lisa