Please note that the size listed in the popup is the "scaled size" of the annotation, which accounts for the density and resolution of the screen. So if you select a value of "6" for the height, for example, this will be saved as a much smaller value in terms of the raw PDF page size, so it could be something like 2.42. If that annotations is rendered on another device, it will scale that 2.42 to match the density and resolution of the screen, so the size could be something very different like a scaled size of "4" or "8". That is why you are seeing the height listed as a 3 on your PC - the display scaling in Windows is most likely a smaller value like 100% or 125%, whereas on your Android device, it probably has a display scaling of 200-250%. However, I'm not sure why modifying it on the PC would cause it to suddenly become a different size on the Android device, as the scaling should still be consistent between devices for the selected value. Are you using a PDF or text/ChordPro file?
Mike
Mike