You can use the button editor to create or edit a button's style. You can create a new style or use preset styles. You could also save the custom style as a new button for future use in other sliders and slides.
There are a lot of options for you to style your button and apply them with the option of seeing changes in real-time preview.
If you remove a button from the list it will affect other sliders that use this specific button as well and their style would be removed.
The figure below shows these options on Master Slider panel