Use the "Skin Color" slider to change the skin color of the Yuu, press the buttons to the right of the Yuu to change their hair, eyes, and mouth, the buttons underneath the Yuu are to change their nose, and the Hair Color/Hair Brightness sliders, do what they seem like they'd do. The buttons to the left of the Yuu are to change its facial hair. Click the torso to change its color. The two big buttons on the left side of the screen are to Save (floppy disk) and Load (open folder). The Save allows you to copy your Yuu code, and the load allows you to a load a Yuu.
Share Yuu Codes here: https://scratch.mit.edu/discuss/topic/889742 This is the Yuu-Maker. It's practically a decent (emphasis on decent) Mii Maker for Scratch. The main usage is going to be for an upcoming game, based off the Tomodachi Life series (Collection, Life, and Living the Dream). Credit to: Nintendo for their music and basic idea and Scratch Team for their coding platform.