To update a GZCMS theme that was published with a left or right sidebar menu/header so that the menu is oriented as a top menu, see the following instructions.
First, log into GZCMS and open CUSTOMIZER.
Next, navigate to HEADER > HEADER LAYOUT then adjust the LAYOUT dropdown accordingly.
This may require customization to the menu's options as to how much space and items are allotted for the header type which can be done via the individual menu options.