So I have some text, and I've put a horizontal line above the text using "Borders". It puts down a thin line. I click on the line, and can adjust the width, color, transparency etc. Then I save the document. When I reopen the document, the width, color, and transparency adjustments for the line are gone, and I'm back to the original thin line. How do I preserve what I made the line look like?

I'm using Word 16.16.27 (Mac).