Globally (whole website unless overridden)
E-commerce > Product View Options > Display Format.
Per Product:
You can set the change the display format for your options via the Product Options - Selection layout area found on the OPTIONS/SIZES page.
Simply choose the required option you would like to show from the relevant dropdown.
Single dropdowns are only available for Product Variations not Simple Product Options. Setting a Simple Product Option to a Single display option will still show multiple drop-downs or radio buttons.
As indicated above Product Variations can make use of the single display options as well as the multiple display options available. Below shows some of different formats.
Each product can have its display options set per product by changing the setting in the OPTIONS/SIZES area. You can also set a default for all products via the E-COMMERCE > DISPLAY OPTIONS area of the CMS using the same options.
You can choose a specific display option in the CMS, which works independently of the display options set in the website.
Bottom left menu is "Settings"
In settings you can override the option format on a "POS user basis".
This overrides even unique product display option choices as set via the product options area.