Can you be more specific? Which field in Admin --> Language can I edit the text? Which file can I change the image and the favicon image?
Also, I already have a "self-signed certificate" and would like to get a "real certificate" in order to have this instead of this I'm confused by the steps you have listed on your site. Do I have to remove the current keystore.jks, truststore.jks and keystore.jks.old and start from scratch? What is the difference between creating a keystore from scratch and using existing key-pair? Which one should I follow?
