As system administrator, there are two different ways to edit the system administrator's user clients:

Option 1: Select the menu item User data - Clients via the menu. 

Option 2: Via start page and the tile Clients

All clients that have been created in the system are displayed here. The respective client can be edited via the Edit button

A detailed description of the settings can be found under:

Client Master Data

The entry or change can be saved via the Save button.