I usually use medium temperature on my Helen of Troy curling iron brush. I don't like the lowest because my hair doesn't stay curly all day and highest because it can damage my hair. If you need curling iron with the very high temperature you can read descriptions on this blog https://mystraightener.com/10-best-curling-irons-reviews/ and find best for you. And if you really want to use high temperature never forget about hair protection to don't damage it so much.
Without continual growth and progress, such words as improvement, achievement, and success have no meaning.