React native: header styles in navigationOptions not working

I think you are using react navigation version 3. If so navigationOptions is changed to defaultNavigationOptions.

{
        initialRouteName: 'Calendar',
        defaultNavigationOptions: {
            headerStyle: {
                backgroundColor: '#28F1A6',
                elevation: 0,
                shadowOpacity: 0
            },
            headerTintColor: '#333333',
            headerTitleStyle: {
                fontWeight: 'bold',
                color: '#ffffff'
            }
        }

}

It should work. https://snack.expo.io/ByGrHdAC7

You need to use defaultNavigationOptions.

Admittedly, they didn't even mention that they changed it between v2 and v3 in the docs!

https://reactnavigation.org/docs/en/stack-navigator.html

to setup custom react react navigation you need first defined option.navigations or option.defaultNavigationOptions in your App.js

App.js

 <Stack.Screen
                 name="ListeMedocItemScreen"
                 component={ListeMedocItemScreen}
                 options={ListeMedocItemScreen.defaultNavigationOptions} // ListeMedocItemScreen.navigationOptions

  />

then in your conponents page

if you use hooks

const ListeMedocItem = (props) =>{
  //some component
}


ListeMedocItem.defaultNavigationOptions = ({navigation}) => {

  return {
    title: 'My home',
    headerStyle: {
      backgroundColor: '#f4511e',
    },
    headerTintColor: '#fff',
    headerTitleStyle: {
      fontWeight: 'bold',
    },

 }}

or if you use React.Components

static navigationOptions = ({ navigation }) => {
    //return header with Custom View which will replace the original header 
    return {
      header: (
        <View
          style={{
            height: 45,
            marginTop: 20,
            backgroundColor: 'red',
            justifyContent: 'center',
          }}>
          <Text
            style={{
              color: 'white',
              textAlign: 'center',
              fontWeight: 'bold',
              fontSize: 18,
            }}>
            This is Custom Header
          </Text>
        </View>
      ),
    };
  };

Just simply change your navigationOptions to defaultNavigationOptions and it will work fine

Thankx!