This guide shows you how to change the default language within your WHM.
1. Log into your WHM as root user
2. Once in the WHM interface, search and select "Tweak Settings" option from the left hand menu
3. Once within the Tweak Settings's interface, within the search box, search for "Server Locale"
4. Click on the drop-down box from the Server Locale options, select the desired language
5. Click "Save."