I have an Ubuntu Amazon EC2 Instance that I need to access, update and delete files via FTP. Only the root user has access on this though, so I need to enable a specific user to modify them. To do this, login into SSH of your Amazon EC2 instance, then type these commands; change ubuntu into your user then press Enter for every line break.
sudo -i chown -R ubuntu /var/www/html chmod -R 755 /var/www/html
After this, try again if you can now transfer, update and add files via FTP.