
Turning off the "Detect language automatically" option should help with future text that you add. However, for any existing document, you will have to select all and then re-apply the correct language using the Language dialog box. In Word for Windows, first select all with Ctrl+A. Then click Review tab > Language group > Language > Set Proofing Language. If the dialog box includes radio buttons for "Selected Text" and "Current Document," pick the former option. Choose the appropriate language. Click OK to confirm.