Accessibility Remote Ok/Select button not labeled

My mom is living with dementia in the early stages. She can FaceTime on an iPhone, but cannot work this accessibility remote. Why isn’t the black button that is used to select not labeled? The number of people living with dementia and Alzheimer’s is expected to triple in the next five years. Has anybody figured out a way to label the button so that it stays labeled even if your thumb hits that button a lot