Sorry for confusing you. The fact is that you've already made the changes, so to find out the reason why the icons do not appear or how come that the color of the highlighted column is differs from your main site palette, we need to check it at your website directly. Also, the styles may be different from theme to theme, so the solution we will provide may not work at your theme.
Anyway, here is the styles for the Simplicity theme:
To change the highlighted column color:
.ow_highbox_table .ow_highbox, .ow_highbox {
background: red none repeat scroll 0 0;
border: medium none;
box-shadow: 0 0 1px #eff2f5;
}
replace the red value with the color code of your choice.
To change the icon you should use these styles:
html body div .ow_ic_ok {
background-image: url("images/ic_ok.svg");
}
replace the images/ic_ok.svg with your image URL. You can upload your custom icon via Admin Area > Appearance > Customize > Graphics tab.
All the changes can be done via Admin Area > Appearance > Customize > CSS tab.
If this doesn't help, you can PM your website URL and test account access details.