To get your keyboard back into the British format please follow these steps;
1. Right-click on the Windows icon (bottom left) then press 'Settings' 2. Click on 'Time & Language'
3. Select 'Language'
4. Click 'Add a preferred language' then type "United Kingdom" into the search bar
5. Double click on English (United Kingdom) then press 'Install'
6. At this point, you will now have two languages installed, to remove the United States language press on it then the down arrow
7. Once you have moved that down you will be able to remove the language from your PC, like so: