Featured Slider "Custom" doesn't work

Hi guys, I'm trying to use the Featured Slider > Select Slider Type not with pages but custom. But I can only change the image. My custom Title, Subtitle or Content does not appear. Can't change it using the customizer - there is still the Demo-Content shown. Can you help me with that? And I would love to change the height of the Slider to make it a bit shorter. Where can I change that? Thank you so much. Best wishes!