When We fix the resolution as 480 × 640. Write this. In AppDelitege class. On applicationDidFinishLaunching

// initialize director
auto director = Director::getInstance();
auto glview = director->getOpenGLView();
if(!glview) {
	glview = GLViewImpl::create("My Game");
    director->setOpenGLView(glview);
}
// set resolution size
glview->setDesignResolutionSize(480, 640, ResolutionPolicy::EXACT_FIT);
		

I fix resolution 480 × 640.