Here, it explains how to change the color of the choice button.
(1) Click on the setting button on the upper right of the management page.
(2) Click on [Chat]>[Design]>[Template] on the left side of the screen.
(3) Click on [Detailed setting] at the bottom right of the screen.
(4) Choose the color of [ Choice background], [Background's color when the choice is hovering], [Background color of choices after clicked], [Color of letters in choices], and [Color of letters in choices after clicked].
(5) Click on [Update].