Windows 10 IoT does not offer a possibility to set Time Server with a GUI as you know from other Windows Operating Systems.
The selection you see in the Cover Image does not exist.
But there are other posibilities....
Get Timezone Properties
Set Timezone with Powershell
Enable Time Service Logging
e.g.: w32tm /debug /enable /file:D:\w32tm.log /size:1000000 /entries:0-300
example of a logfile
Query Time Service Configuration
w32tm /query /configuration
Query Time Service Parameters from the Registry