RootStackNavigator.js

import { createStackNavigator } from '@react-navigation/stack'
const Stack = createStackNavigator();

const RootNavigator = () => {
  return (
    <Stack.Navigator initialRouteName='password'>
        <Stack.Screen options={{title: 'Password'}} name='password' component={PasswordScreen} />
        <Stack.Screen options={{title: 'Chat', headerBackTitle: 'Logout'}} name='chat' component={ChatScreen} />
    </Stack.Navigator>
  );
}

export default RootNavigator;