Thanks for the screenshot!
The color that you've just changed is only for the button's icon color.
To change the background color of the button, you need to disable the "Use the same style of the main button".
You'll then be able to change the color of the button. 🙂
We recently did some internal UX test and found out that,
yup😐, it was a bit hard to find the background color option.
We've made it easier to find that option and we'll include it in an update!😁