The Slider Settings section in the Event theme Customizer contains 2 options. Navigate to Appearance → Customize → Theme Options → Slider Settings to access these settings.

Options

• Slides (Repeater) — Add slides for the homepage slider. Each slide has an image (recommended 1920×714px) and alt text.
• YouTube Video ID (Text) — Enter a YouTube video ID to display a video background instead of the slider.

After making changes, click Publish at the top of the Customizer to save your settings.