Cannot edit new color theme option

We just installed the new update and some of the feedback we got from our staff here is that the blue text in the requests tab would be better if it was black text. I can't find a way to edit this text. When I go into "Admin > General > Theme", I see there looks like there would be an option to change some colors, but the "Custom Color" radio bubble is grayed out and i cannot change the "default color". Also even if i could change the default color settings, i don't see an area to change the text back to black like it was in the 8.1 update. If you look in the image below "custom color" is greyed out. Is there a way to revert the text color or change it? Is there a reason why the color option is greyed out?