Palettes in RMv2 are set for individual layers, not for the map project as a whole. This allows different palettes to be set for isobaths, shaded relief etc. Where are you trying to change the palettes now, and for which project layer? You need to open up the layers tab, select the layer you want and then adjust the palette as required. If this isn’t working, please let me know and show a screen shot of what you are doing.