Under Client Config Order: Extras: set Extras: Show on the Cart Preview Page to Yes to list extras on the cart; Extras: Add a Popup on the Cart Preview Page opens them in a pop-up, and Extras: Show Popup on Every Load repeats it on every visit. Extras: Title, Extras: Subtitle and Extras: Description change the wording and Extras: Display by category groups them by product category. The equivalent switches for products are under Order: Product (Products: Show on the Cart Preview Page, Add a Popup, Show Popup on Every Load).