Open the old Control Panel
At the top of Control Panel, set View to Icons
Select Region
Select the Administrative Tab on the resulting dialog
Click Change System Locale in the 'Language for non-Unicode Programs' section
Set the language in the drop down to the same as the System location/Language
.
Open the Settings App, then go to Time & language - Language & region
Scroll down to the Additional Settings section.
There are two 'Copy current... ' sections in there, click the Copy button in each section.
Restart (not shut down) the PC to apply the changes.