To change the default keyboard language in Windows 10, you need to go to the Settings app.
1. Open the Settings app. You can do this by pressing the Windows Key + I.
2. Select Time & Language.
3. Select Region & Language.
4. Under Languages section, click on the Add a language.
5. Select a language from the list of languages.
6. Once you have selected the language, click on Options button.
7. On the Options page, you can select the desired keyboard layout for this language.
8. Then, click on the button Set as Default to set the selected language as the default language. You may also need to select the checkbox labeled Let me set a different input method for each app window.
9. Click on the Save button.
10. At the bottom of the page, you will see a list of currently installed languages. The one marked with a blue tick mark is the active language; and this language is used as the default input language in Windows 10.
The above steps should help you change the default keyboard language in Windows 10.