How to exclude the header from sorting in calc?

When I try to sort a table the header gets sorted as well. Which is quite annoying. And if you don’t undo it immediately can destroy work of months in seconds.

I have a followup question/comment:
First, the answer to this question is ridiculously difficult to find, and I’m glad I did find it.
But, having used the software for years, I know “Range contains column headers” must be checked by default, and rightfully so! Then, since I know for a fact that I’ve never unchecked it…how does it get unchecked???

open Data → Sort → register: Options

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