Thanks for taking the time to reach out to us. Let me help walk you through on how to turn on spell checker in QuickBooks Desktop.
Click Edit menu, then choose Preferences.
Under MyPreferences, mark check Always check spelling before printing, saving, or sending supported forms box.
You can identify words to ignore as well as add custom spelling words on the same preference page.
By following the steps above, the auto-correct should now be enable. Don't hesitate to leave a comment below if you have additional questions about the auto-correct. I'll be around to help. Have a great day!