Working with the app interlocking parts

When I have a project that has interlocking parts I am having trouble resizing the locking holes. It seems that each time I select an item and go into the interlocking app program the program is putting in another hole or interlocking piece some where else in the piece and it still has the original location there too. I have tried to move the extra locking area to where the original one is I can’t. How can I resolve this so I can change my work piece thickness and change my interlocking area to fit the thickness of work.