A little more information about what changes you are making would help in understanding what is going on.
Generally, the program works on a model which uses the brew house efficiency to determine the amount of sugars which make it into the fermenter. Changing any water volume except for the volume to fermenter will not change the values at all, as the program just recalculates the amount of sugars extracted from the mash.
The calculation of color and IBU is similar in response.