The reason why this color is not yellow is because your screen on your phone, tablet, computer, playstation via, or DS only produces green, red, and blue light. Extremely small pixels of those colors. Red and green pixels that are next to each other (an extremely large amount of them) create this optical illusion of yellow. Our retinas in our eyes can't process the small light points so it looks like yellow. (It makes our brains think that) well thank you for reading this long long paragraph! :)