@humani1 - In addition to the wiki dnolle pointed out, you can also find a short overview about this in this thread in the First post - go to the section labelled Calibre Tips and look for Book Titles.
@dnolle - thanks for the pointer. Actually, there are a lot of features to Calibre and they aren't always easy to find
I've just added a tip as a result of your post to the First post in this thread under Calibre tips. It describes how you can set the output for Mobi files to set Author to Lastname,Firstname in the book when its sent to the Kindle. This does not change the Author field in Calibre. But as you mentioned, the Kindle recognizes the comma in the name and converts it to firstname lastname when displaying.