I've used knockoff "post-it notes" things to point out the mode and OK buttons on my monitor because the text to show what they are is black on a black background and the text is raised and glossy on a matte (ish) background and when my hand is there fumbling to reach the buttons it blocks the light making it EVEN HARDER to read the text so I often press the wrong buttons and turn the monitor OFF instead of switching the input source so I can play on my Rpi or switch back to my PC...