I realize this post is old, but I had the same question, which led me to this post.
I read through all the replies, but none of them answered my question (I interpreted the original post as having the same question I have).
My question: If you make a pie chart in excel and use patterns instead of colors for the different slices, it is very difficult to see those pattern differences in the legend icons. How do you increase the size of the squares (legend icons) so that the pattern
differences are visible?
My temporary solution was to increase the size of font of the overall legend box and then make it a superscript. (can be done by right-clicking, selecting Font, and checking the superscript check-box). This should keep the square icons enlarged while shrinking
the text. You can then also change the superscript offset amount to change where the text is aligned.
This solution only allows an icon box up to a certain size though as making the text superscript will only shrink it a predetermined amount as far as I know. Also line spacing on the text seems not possible since it is a superscript...