I'm using AE CS5 and have an animated logo that has both green lettering as well as yellow lettering... is there anyway of changing all the lettering to green?
Change To Color effect
found with this search
You might also want to try Fill, Tint, Colorama, Hue & Saturation.... You may even be able to use the logo as a track matte for a solid or a shape layer.
Your results will depend on the logo. A screenshot of the logo would help.
Retrieving data ...