Why can't I change the notification sound on Message+ for Galaxy S8?
whitneykakey, let us help you get your S8 Verizon Messages customized to the tone you like. You will be able to make changes to the notification sound in the Verizon Messages + App by tapping on the 3 dots located on the upper right part of the app. Here you will be presented with the option to select "Customize" and then you can select "Tones" to be a notification sound that you like.
Happy Messaging!
yarelim_vzw