You have to edit this in skin.xml
Skin default MX_Titanium_C folder
<screen name="ChannelSelection" position="center,105" size="1820,880" title="">
<eLabel position="1208,18" size="570,324" zPosition="2" backgroundColor="black"/>
<widget source="session.VideoPicture" render="Pig" position="1228,30" zPosition="3" size="530,300" backgroundColor="#ff000000"/>
<ePixmap pixmap="MX_Titanium_C/menu/menubutton.png" position="1730,815" size="48,48" alphatest="blend"/>
<ePixmap pixmap="MX_Titanium_C/menu/epg.png" position="1660,815" size="48,48" alphatest="blend"/>
<widget name="list" position="10,67" size="1180,810" scrollbarMode="showOnDemand" enableWrapAround="1" foregroundColor="white" progressBarWidth="80" fieldMargins="13" foregroundColorServiceNotAvail="#999999" colorEventProgressbarSelected="white" colorServiceDescription="#afafaf"
...
....
you can use hex color code or use exiting colors
example:
colorServiceDescription="yellow"
or
colorServiceDescription="green"
or
colorServiceDescription="blue"
Quale colore vuoi ?