After you have written a text and run spellcheck, you might find it necessary to go back and revise the document. You might also have found that you have been running spellcheck, your brain has gotten a little numb, and you can't remember if you actually fixed the last error or just "Ignore" automatically. You'll need to re-set your spellchecker so that it will recheck the entire document, not just new text that is added. Here