If you are trying to make it dark or one color and you have gamma correction checked bryce will try to undo your changes in the render. If you have sunlight on or link sunlight to view it will affect how thet other lights you load into a scene work, same for the render quality. There's lots of little different windows to open to correct these things plus there are the material settings that affect how your objects react to the light they get. A picture is worth a thousand words. If you post one of your renders we can see what is going on.