JavadM,
How you change the color will have varying effects. If you just want to do it as needed, Ronald's method will work fine. If you wish to change the color of all solids permanently, then you can either edit your customer defaults (for files using the Blank or no template) or if using a template, you can open the template, make the change via Ronald's suggestion and save the template.
Tim Flater
NX Designer
NX 11.0.1.11 MP8
GM GPDL 11-A.3.3
Win7 Enterprise x64 SP1
Intel Core i7 2.5GHz 16GB RAM
4GB NVIDIA Quadro K3100M