It’s seemingly still bugged. We actually reported the Xbox controller issue of not being able to select the “next” and “previous” designs with the single arrows at launch and it was acknowledged, but yeah…

What works (just tested it again) is to select the double arrows next to it (see image) which then lets you jump to the next page with more designs by pressing A.

Regarding the color, select the small arrows left and right of the color sliders (see image) and press A to move the slider either right or left. Hope that helps!