I have a hard time believing this. My six year old has been using that menu just fine for years now, and on my phone (Galaxy S9+) one of those settings is either dark grey with a light gray icon, or bright blue with a white icon. It's hard to imagine being confused by that. Maybe your menu looks significantly different?
My phone that uses default stock android system have darker grey and lighter grey for on/off. It's difficult. Samsung uses modified skin on your phone.
Under Settings > Styles and Wallpaper there are a few different options. I think the default is blue for selected, but you can select "Ash" to make it grey vs grey.
