I am trying to change the color of the GIF file. How can I do this?
I couldn't do it with Hue saturation.
As GIF files open in indexed mode by default, you might want to try converting the GIF into RGB mode (menu Image -> Mode -> RGB). Then change it using the Hue/Saturation/Value tool (menu Colors -> Hue-Saturation) and then converting it back into indexed before saving it.