I'd be careful with the bleach stuff, it's very possible that the bleach will make the white a different shade than the rest of the mouse. See if using something like a magic eraser will clean the yellow off, it may just be buildup on the key and not a color change of the surface. If that does not work, then try the bleach stuff but make sure there is very little liquid on the wipe, wring it out first so it's moist not wet.