Hello, Mario!
You are right, unfortunately, there is a small bug in the theme.
Temporarily, until we fix that, you can change the color on ALL slides using next code:
(Insert it in: Customizing->General-> Additional CSS).
#agama_slider .button-border {
border-color: #fe6663;
color: #fe6663;
}
#agama_slider .button-border:hover {
background-color: #fe6663;
}
If you want to change the color on the particular slide then you need to use the next code:
#agama_slider .slide-2 .button-border {
border-color: #fe6663;
color: #fe6663;
}
#agama_slider .slide-2 .button-border:hover {
background-color: #fe6663;
}
In that case, you will need to change the slide number in the code, per your needs.
Best Regards