Many times shops has less FAQs so categorization isn't helpful. App allows you to show all FAQs without any categories. Turn on following option to show all FAQs flat.
1. Visit app "Design & Settings" and then navigate to "Display settings".
2. Check option "Don't categorize FAQs (This would show all FAQs flat)" and save settings.
Note: If you are using "Template 2" then note that you can't use this option as template 2 requires presence of category.