1. All styles are in dynamicStyles at the end of App.js, however some items from header don't have styles, then you need to create new style, for example:

    myStyle: {
        color: red,
    },

and apply it where needed, for example:

<Button transparent>
    <Icon style={styles.myStyle} name='search' onPress={o.onSearchMenu} />
</Button>

 2. It's some sort of bug I think in the theme library which we're using for UNA mobile app, but you can try to play with this code (particularly with setBarStyle), by removing functionality for dark//light mode support and make it static, so it should work then:

        const isDarkMode = useDarkMode();
        var sBarStyle = 'dark-content';
        if (Platform.OS === 'android' || isDarkMode)
            sBarStyle = 'light-content';            
        if (Platform.OS === 'android')
            StatusBar.setBackgroundColor('#076fd3');
        StatusBar.setBarStyle(sBarStyle, false);         

#mobileapps

3. Alexey could you please assist with this point ?