Every word I type into an Open Office document appears with a red squiggly line under it. It was ok a little while ago. I think (but not sure) that it started happening after the last windows 10 update.
It's not a huge problem as I only use it to write out quizzes for my local club.
Nothing too technical please.
The red squiggly line means a spelling error. The chances are that you've set it up with automatic spell check, but not installed/configured the correct dictionary.