Function change_setting 

pub fn change_setting<T, Action, Requested, AppAction>(
    settings: ResMut<'_, Persistent<T>>,
    action_messages: MessageReader<'_, '_, Requested>,
)
where
    T: Resource + Serialize + DeserializeOwned + SettingActionHandler<Action>,
    Action: Copy + TryFrom<AppAction>,
    Requested: Message + RequestedSettingAction<AppAction>,
    AppAction: Copy,

Shared settings system set and helper systems.