It is the same in the full versions. Since i generally don't like using the field names as the titles, I have turned the option of inserting the field header off so I hadn't seen that.
Crystal actually calls the one a field header and the other is a field so Crystal does consider them different.
I don't see an obvious way to turn it on. Perhaps that is because you know how big it is when you design the report and can change the size appropriately especially since the text is static you can set the size during design.
Are you doing something that makes the heading change size?
mlmcc
