Sometimes I find that moving the bottom margin up does not have any effect.
I'm moving it up by dragging the bottom blue bit in the vertical bar on the left of the page.
This is particularly frustrating when you want to get some text from the bottom of one page to move to the top of the next, or to get text at the bottom of one column to migrate to the top of the next. I can move the bar right up well above the bottom of the text and it just stays where it is.
Does anyone have any solutions for me?

Thanks