Splits have to be selected to be included in report each time

I have a report called Medical YTD, its categories include medical costs and insurance costs. Some transactions have splits i.e. Medicare premiums are contained within a Social Security income transaction. My problem is the report works fine except for the splits which I have to manually select every time I run the report. Why won't show splits be saved in the report?
Similarly, prescription costs sometimes have non-prescription items, which show up as additional medical costs unless I manually selected show splits.