You can change the color scheme. Documents Settings > General Tab > Color Sheme (Drop Down) on the right side bottom of the window. If you change it from Classic to Lime or something else then you can see the font color in black.
you can change the background, closed color and style in presentation tab. Not sure about font color in multibox about my knowledge..
Hi Go to the caption and change the Background colour , when active and background colour when inactive. It will be On the caption bar. If you want the color to be on the background of the fields go to presentation and change the closed color option which is available.