Up until r66.18, I used to be able to just edit the instance of a bill, and the edit would be remembered whenever I entered the transaction into my register. Other future instances of the bill were not affected. I edited an instance of a bill on February 14. Today, I went to enter the edited bill and noticed that even though the amount shown on the current bill column was correct when the bill window (enter expense transaction window) opened, my bill reflected the regular bill and not the edited bill. Had to recalculate and re-enter the bill again.
[Edited - Readability]