Windows 10’s localisation options seem needlessly convoluted, and we’ve had multiple reports of incorrect localisation even in computers that were upgraded from correctly localised Windows 7 or Windows 8 installations. The most common issue seems to be dates in the American format MM/DD/YY, but Windows can also report that Cortana isn’t available, even in regions where it is.
From the Start Menu, search for region and choose Region & Language settings. Check that United Kingdom is selected under Country or region, and check that your chosen language(s) appear under Languages. Select your primary language, click Options and click Download under the language pack, and speech options if they’re present. Check on this page that the keyboard is also correct – if it isn’t, add the correct one then select the wrong one and remove it.
Click the back arrow and select Additional date, time & regional settings. Under Language, click Change input methods, select your chosen language, move it to the top of the list if it isn’t there already, and click Options. Under Windows display language you might see either Enabled or Available – if the latter, click Make this the primary language. If you don’t see either, download and install the language pack, then make it the primary language.
Click the back arrow to return to the language preferences, and in the left-hand pane click Change date, time, or number formats and check that the format is set to the correct language. Check the Home location on the Location tab, and finally use the Administrative tab to check the System locale, and use the Copy settings button to apply the settings to the Welcome screen and new user accounts.