ADXL345 information/help/problem/guidance etc :)

Question:

To measure G forces, I'm using that code:

#include "ADXL345.h"
ADXL345 accel;

...

  accel.powerOn();
  accel.setFullResBit(1);
  accel.setRangeSetting(8);
  accel.get_Gxyz(xyz);

Is it correct? When I'm changing from 8 to 2 or to 4 for example, I get different readings. I just want the upper limit to be more than 4 Gs.