iOS Kindle app reader question.

I’ve been using the Kindle iOS app and I recently turned on the accessibility reader in iOS and try as I might I can’t seem to get the voice to change. I’ve watched tutorials on it on YouTube etc and I’ve followed them to a t but every time I change the voice nothing changes in the app. I’ve rebooted the phone, deleted and reloaded the app but nothing seems to work. Am I doing something wrong? Not even sure if this is a phone or app issue. Any help that could be offered is appreciated.

Thanks