how to make captions on rewind (skip back) last for 30 seconds

In the setting of my Apple TV it’s says when you turn on captions for skip back it’s up to 30 seconds, but in reality when I rewind/ skip back the captions only come on for 10 seconds, and also state on the screen it’s only for 10 seconds. There doesn’t seem to be any setting to make this 30 seconds as advertised - does anyone know how? Support we’re unhelpful and told me to do a restart