Roku TVs may suddenly begin narrating on-screen text because their Screen Reader accessibility feature has been activated. It is designed to help visually impaired users navigate menus, but can be switched on accidentally through the remote’s shortcut.

To turn it off, press the Options button, marked with a star, four times in succession. Alternatively, disable Screen Reader through the Accessibility menu, where you can also turn off the shortcut to prevent it being triggered again accidentally.