How to change the Slider Content Background Color

Hallo, I would like to change the Slider Content Background Color and try to do this by going to: “Appearance => Customize => Color Options => Slider Color Options” and then adjust the color in "Slider Content Background Color". First of all, I presume that this is the correct menu? If I change the colour setting there f.i. in #888888, nothing happens. If I use one of the preset colour buttons below the "colour selector", nothing happens in the text field either, but there appears a coloured strip of about 1 cm height, below the slider image frame in the newly selected colour. I have the impression that the menu is not properly functioning And if I'm using the wrong menu, can you please advise where I can find the correct one? Tank you!