First: Select the desired color with Select -> Color Range ... by holding shift and click we can add the colors we are interested in.
Second: Because the selection is on dark background we need to use Blend if in the layer options. Adjust by eye.
Third: Add an Hue/Saturation adjustment layer to change the color.
Extracting Colors from an Image
GIMP USE CASE
Sample output ("Yellow channel") (gray background to see details)
Sample use case (Color exchanging)
As colors are the focus of attention in this kind of workflow, please ever set the 16 bit color depth mode AT THE MINIMUM before any manipulation, and make sure to work in a ...
There are so many different ways to do this. Different images respond well to different methods, so it's good to have a whole arsenal of different approaches.
I can't show them all here, so I'll just give you one example.
Separate yellow with Black & White adjustment
If we can create a grayscale image where everything yellow is white and everything else ...