A majority of FreeScout's configuration can be modified via the WebUI. However, if you must modify the DB details, for example, you must do this in the .env config file. Simply changing the values in the file will not work; the changes must be applied by using Artisan.
Make your change(s), then run the following command inside the installation directory (/var/www/freescout/)
php artisan freescout:clear-cacheYou may need to re-apply the owner and group on all files
chown www-data:www-data -R /var/www/freescout/*