How can I change screen title in page

Modules:

"react-native-router-flux": "^4.0.6",
"react-native": "https://github.com/expo/react-native/archive/sdk-33.0.0.tar.gz",
"react": "16.8.3",
"expo": "^33.0.0",

I tried

    Actions.refresh({title:'newTitle'})

But it happened.

I want to change title not back title