Hi dougadan!
This is happening, because of the Edit Slider -> under Slider Settings -> Global fonts. They have defaultly different values for different devices, to keep them readable, but you need to have your layers big enough to show them. If you click on your slides with the Manual slider, or go to the Generator -> Edit Layout with the Quick slider, or other Dynamic slider, then you should change the view to tablet and mobile view, and you should adjust your layers in there.
Or if you are using big enough fonts, and you don’t really need bigger fonts on smaller screens, then you could just change the Global font sizes to the same value. You can read everything about the responsivity of our slider in here, also there is a video: https://www.nextendweb.com/wiki/smart-slider-documentation/responsive-mode/