To change the top menu module menu style please complete the following.

  1. From the Joomla Administrator area select the extensions menu and modules manager menu

  2. Now select the top menu module which needs to use the position-1 module position.

  3. In the Menu Tag ID field enter navĀ 

  4. In the Menu Class Suffix field enterĀ  -nav

  5. To enable the drop down menu for the top menu position set the "Always show sub-menu items" to YES

  6. Click on the save button.