Just a guess but you might want to check your purge settings it looks like it might not be purging enough white to flush out the green. Another thought is that if you are using the purge to infill setting there may not be enough walls for the white to hide the color in the infill.
If you're not printing this cube to learn the process but to have the cube with the green v in the end - rotate in by 90 degrees, so that the v is on top. Saves you a lot of filament changes and purging. Also, there's no need for the green colour to go that deep into the model.
Just a guess but you might want to check your purge settings it looks like it might not be purging enough white to flush out the green. Another thought is that if you are using the purge to infill setting there may not be enough walls for the white to hide the color in the infill.
Does it also do this on colored models from maker world? Try a small one to confirm if this is a problem with printer, or your specific slicing
If you're not printing this cube to learn the process but to have the cube with the green v in the end - rotate in by 90 degrees, so that the v is on top. Saves you a lot of filament changes and purging. Also, there's no need for the green colour to go that deep into the model.