Overriding layout of existing/sample categories in magento

I have installed Magento with sample data. It has categories and products. I added one new category to default category. I followed some tutorial to change the left and right sidebars via XML below is my xml

<?xml version="1.0"?> <layout> <catalog_category_default> <reference name="root"> <action method="setTemplate"><template>page/2columns-left.phtml</template></action> </reference> <reference name="left"> <remove name="left.permanent.callout" /> </reference> <reference name="left"> <remove name="left.newsletter" /> </reference> <reference name="left"> <remove name="cart_sidebar" /> </reference> </catalog_category_default> </layout>

For my newly created category the above xml works fine ie remove the left sidebar items and also loads 2 column layout as I specified in the xml. But for the existing categories it is not working. I also went to edit the existing category and in the design tab I changed every thing to default. Mean it is not using any overrides from there. Can any one please tell me is there any other panel or xml where these categories pages are taking templates from. Thanks in advance.