So if you're still reading this, you're probably wondering how to change sprite colors. There's two options... one much easier than the other.

First off, you could go edit both of the sprites, pixel by pixel, changing it's colors. This is very time consuming but actually done often by ms paint users who want to draw pixel art. I'm not sure why!

The easier way depends on how you would want it done. You can play around with color hues in your favorite graphics program like Adobe Photoshop. You can also set your graphics to both use a limited amount of colors, like 256. The less you have is easier. Have both of your sprites use the same color pallete (export and load it).

Once you're on the palette, you can change the colors individually. Head into the editor and pick new RGB values for each of them that you're unhappy with. These are little sliders that control the amount of red, green, and blue in the color. There's actually no limit in real life to the amount of color you can see, but computer sprites are limited in what can be displayed on the monitor. Once you're done with the changes to one sprite, export your palette and load it for the other image too. This way you'll be able to have your graphics match easily!

You can also batch transform the palette using colorization tools. This can save a lot of time, but they often turn out horribly bad. These are also an option in Adobe Photoshop and some other image editing programs.