Widows and Orphans

This might be the wrong place for this post, but I'm having issues with widows and orphans on my Clara HD. I followed the steps to remove widows and orphans when converting books to epub. However, some still have inconsistent bottom margins even after this process. I downloaded The Wheel of Osheim and by Mark Lawrence and The Silver Tide by Jen Williams from Amazon. Different publishers, both AZW3, and still had inconsistent bottom margins after conversion to epub following the widows and orphans process. Is there anything else I can do?