Apply changes to multiple parent pages

Hi everyone

Does anyone know if it's possible to make changes to all parent pages at once, or do I need to do the same thing for each one?

I have a long document (200+ pages) with about 16 different parent pages. I want to change the number of columns for the entire document but I don't seem to be able to select all the parent pages. Do I have to go into each one individually to make the same change?