Thank you for your post.
First, I notice in your screen shot you have two tabs open for Admin Console. Why?
After uninstalling FileMaker Server 14, did you remove the FileMaker Server folder?
In case the Header information was cached, reboot the server, launch FileMaker Server 15, and then launch a browser and access Admin Console. Does this still show "FileMaker Server 14"?
I administer multiple servers, the second tab is another server instance.
Although I did do a server reboot after upgrading and did not remove the filemaker server folder,
It looks like the browser caching is to blame.
After a computer reboot it shows the correct header.
Let me ask you, is it standard practice to remove the FileMaker Server folder when upgrading?
It is not "standard practice" to remove the FileMaker Server folder when upgrading. Since I have never seen what you have encountered, I tried to think of possible causes, and perhaps an old file may have been referenced. That is the reason for the possible removal of the FileMaker Server folder before installation so that all new files would be installed.
Glad to know the rebooting of the server corrected the Header.