Customise countries flag
To customise the country flags, please access the Geolocation module section on the preferences dashboard. There you will find different options:

Flag style
You can choose among different flag styles. Select the one that better adapts to your store styles.
Flag size
Select
small,
medium or
large size.
Flag position
Select if you want to show the flag before or after the review author and date.
Here you can see some examples with different configurations: