Using Colors Trouble with a grouped model

I am working a model and am having issues adding and changing colors. I select a surface, choose a color and other surfaces change color!?!?

I am relatively new and am working on a model built by others. I believe the groups and components in the model are interlocked and they are not behaving as I expect.

HELP PLEASE!

thats a very broad issue you are raising… can you be more specific and or add the file? Is the surface material named? or is it the default material? you can create your own new material and paint it on to you desired surface… also note there is a difference between assigning a material to a group/component or a surface within a group or component

To add to what @gsharp said, if the issue is with a specific model, share it here so someone can help find an answer.

Have a look at this.