When you’re typing a new document, chances are good that you might not see the red underline because you have “Correct Spelling Automatically” turned on. Normally, this happens in real-time as you’re typing, but if you happen to open a document that’s dozens or hundreds of pages long, it can take some time for your Mac to highlight the spelling errors.
Enable “Check Spelling While Typing” again, and any misspelled words appear with the red dotted underlines. If for some reason you decide to de-select those settings, you’d find that the misspellings no longer appear as underlined.
Want to find the controls for spell checking to see what it’s doing? Click Edit > Spelling and Grammar, and you’ll find that by default, “Check Spelling While Typing” and “Correct Spelling Automatically” are selected. macOS Spell Check underlines words it believes to be misspelled with a red dotted line. What you’ll find is that Apple’s spelling routines underline those misspellings (did I spell that correctly?) with a red dotted line. Open a Pages document on your Mac, and type a paragraph or two with some deliberate spelling errors. Whether you’re using Pages, Numbers, Keynote, TextEdit, Mail, Messages or Safari on your Mac, the same spell check tool comes to your rescue to ensure perfectly spelled documents. Cn u spel OK? Fortunately, Apple has created a spell checking capability that works well in just about any Apple app.
