The headings are background images, not colors. Your template maker has added two layers of divs to the standard one, apparently to allow rounded corners. In your stylesheet, find this
Code:
h3.leftBoxHeading a:hover, h3.rightBoxHeading a:hover {
color: #FFFF33;
text-decoration: none;
}
.sidebox-header-left {
background: url("../images/sidebox_left.gif") no-repeat left top;
padding: 0 0 0 0.3em;
}
.main-sidebox-header-left {
background: url("../images/main_sidebox_left.gif") no-repeat left top !important;
padding: 0 0 0 0.3em;
}
.main-sidebox-header-right {
background: url("../images/main_sidebox_right.gif") no-repeat right top !important;
padding: 0 0 0 0.3em;
}
main-sidebox-header is the top one (Categories), and sidebox-header is the rest of them. Change sidebox_left.gif to main_sidebox_left.gif (and the same for right) to use the orange bg in all boxes.