Select "Edit Club" from the drop down menu.

A window with all registered clubs shows up. Doubleclick on the club that you would like to edit.

You can change the data of the club in the club manager window like the name, shortname or nation of the club.

By clicking on "update" all changes of the club data are saved.

Click on "refresh" to display the changes in the club window. Any change of club data also infects already registered entries with a club.