Text margins question

Good day Ladies and Gentlemen,

Does anyone know how to use the text fixed margins?
They seem to jump all over.

I have found the following explanation in Bubble’s manual.
Can someone interpret it? Having hard time to make sense of the Note at the bottom.
Note: This applies to the first element in the given box, not the selected element.”

Thanks a lot !
Eugene

FROM BUBBLE’s MANUAL

Fixed margin

Choose whether the element preserves the left or right margin when the user resizes the window or accesses the app from a phone. If center is selected, then both margins will stretch or shrink, keeping the element centered relative to its neighbors.
Note: This applies to the first element in the given box, not the selected element.