The Flex Theme Accordions are implemented as a preset on the Visual Composer Accordion Element.
Note: There are two presets, one for Desktop and one for Mobile. If you wish to have the first Accordion expanded on desktop and all tabs collapsed on mobile, you must place the Accordion element in twice in two separate columns, one set with the Desktop Preset and one set with the Mobile Preset, and set the mobile and desktop visibility. You can use the Visual Composer Copy Option to create the second instance and then change the Preset.
Add the Accordion Element to your row.
Choose the Arrow Next to the inserted Tour to Reveal the Edit Accordion Option
Click the Edit (Pencil) Link to open the Accordion Edit Modal and then the Gear icon to reveal the presets.
Choose GSU Vertical Accordion or V.Mobile Accordion and Save changes.