v8 and higher
Select 'Settings | Site Settings | Layout', scroll down to 'Products', against 'Column Count For Products' enter the number of columns you require.
Click on 'Apply' to see the changes reflect in the preview.
Select 'Settings | Site Settings | Layout', scroll down to 'Products', against 'Column Count For Products' enter the number of columns you require.
Click on 'Apply' to see the changes reflect in the preview.