What does "Filter questions" do?
When editing your Additional Questions, you'll see an option to "Filter questions" on the left-hand side of the page.
This option will filter the questions shown on the customization page (no impact on the questions being displayed to the recipient of the survey). Using this filter can help you quickly determine which questions are being shown to everyone, and which questions are being shown to a more select group (ex. Detractors only):