Knowledgebase
How to change the default customer group to which new customers are assigned in Magento
Once a user creates a customer account on your site they are automatically assigned to a default customer group. Magento comes preconfigured with a few customer groups. By default, new customers are assigned to the General group. You can change the default group in which all new customers are put.
Log in to the admin panel of your Magento and go to System menu>Configuration>Customer Configuration button in the Customers section on the left>Create New Account Options panel on the right>Default Group drop-down menu. Select the group that you want from the drop-down menu and click on the Save Config button. This will not affect the existing accounts. Only accounts that are created after you change the setting will be affected. You can change the group of any customer from the Customers menu in the top navigation bar>Manage Customers. You can manage and create customer groups from Customers menu>Customer Groups.