The Multilingual Mix-up
Google Docs is equipped with a dynamic spell-checking engine that attempts to automatically detect the language you are typing in. If you are writing a document primarily in English, but you insert a long quote in French or include a block of Spanish text, Google Docs might automatically change the document’s language locale to match the newly typed section. When this happens, the spell checker switches dictionaries. Suddenly, all of your correct English words are flagged with red squiggly lines because the document is now evaluating them against the French dictionary, requiring you to constantly fight the spell checker.
Locking the Document Locale
To maintain consistent spell checking and stop Google Docs from automatically changing the language based on your typed content, you must explicitly lock the document to a single language.
Google Docs does not have a “disable auto-detect” toggle; instead, you must manually override the language setting for the entire text block. First, press Ctrl+A (or Cmd+A on Mac) to highlight all the text in your document. With everything selected, go to the top menu bar and click on File. Scroll down the dropdown list and hover over Language. A massive secondary menu will appear listing dozens of languages. Scroll through this list and explicitly click on your primary language (e.g., English (United States)). This action forces Google Docs to apply the selected language dictionary to the highlighted text, overriding any automatic detection algorithms. If you continue typing at the bottom of the document, it will remain locked to the language you just explicitly set.