Q:: I want to display menus in 4 columns. Even though I have set 4 columns for menu from admin, It is showing categories in 3 columns at front end and 4th column is empty.
A: Please set the parameter "Merge small subcategories" = "No".
If the parameter "Merge small subcategories" = "Yes" the system try to balance and merge subcategories. Navigate to System-->Configuration-->Custom Menu -->Columns tab
This post is related to the Custom Menu free Magento Extension.
Custom Menu is an advanced free Magento menu extension with Mobile menu and flexible configuration settings that you could use for any eCommerce store.