What do you mean? “VisualARQ materials” are just Rhino materials or those from the render engine you use.
Where do you mean? The VisualARQ layers configuration at the Document Properties perhaps (in Tools > Options dialog)? If this is not the case, can you provide a screenshot?
If it is, in that dialog, you can define in which layer a VisualARQ object will be created according to its type. The material assignment depends if the object has the material assigned by layer, by parent or by style. In VisualARQ templates, all styles have the material assigned By Parent, and since the objects have also the material assigned By Parent by default, they finally take the material of their layer. You can change that and save it as a custom template if you want.
Setting up templates might be something personal and very different from one user to another. VisualARQ templates are meant to be appealing to everyone, as a good start. But of course, you can modify them as you wish and save it as a new template.