The bigger thing that necessarily moving the light is adjusting intensity. If the highlights are falling in the wrong spots or casting shadows in the wrong spots, then moving the light to adjust for this might be needed, but if it is simply producing too much highlight in the right spot, then you need to either dim, gel or shorten the exposure from that light relative to the others.
You don't want to get rid of the backlight, though moving it further back may also help in this particular case. The idea with the backlight is to light up edges to give it more pop and increase edge definition. Ideally, further back is better, but this often results in insufficient power, putting the light in the shot, or simply running out of space due to backdrops and such.
If shadows are too dark, either increase the fill or decrease the key. If image doesn't have enough pop (strong enough edges), increase the backlight or decrease both the fill and key proportionally. If the shadows fall wrong, then move the key, if they don't fill in well, move the fill or include additional fills.