Your primary language is the language that all texts on your website is initially created in. Any other languages you have on your website are translations of the text written in your primary language.
If you’d like to change the primary language of your website, follow these steps.
Go to ‘Content’ and click on ‘Languages’.
Click on ‘Add or remove languages’.
Select the languages you would like to add to your website and click on ‘Save changes’.
Choose the new primary language from the drop-down menu under ‘Primary language’.