Keep the view in the Object Styles window in the same place when making changes to a category or sub-category, and selecting Apply. There are so many categories that you have to scroll down to find what you want to change. When a change is made and the Apply button is pressed, the window will jump back to the top such that you cannot see the category that just changed. You have scroll back down and find it again. It's frustrating and another lack of efficient functionality in Revit's extremely poor User Interface.