Hi,
1. The option to display YouTube video is not available in this default slider.
If you want to show video in slider, you can use Cyclone Slider — WordPress Plugins
- Install the plugin and create slider for homepage
- Go to Appearance » Theme Options » Homepage Slider
- Enter your slider shortcode without php tag
Please check the documentation
https://www.gracethemes.com/documentation/endanger-doc/#homepage-slider
2. To display YouTube video in “Why Choose Us” section, will need to change some code.
Please send your website URL and WordPress admin login details for temporary at support@gracethemes.com so we can make changes in your website.
Regards
Grace Themes