Trying to Change Page Format Across Whole Document

I’ve written a rather large document (several hundred pages) and I’m trying to experiment with different page formats to see which will look best when printed. Unfortunately, each time I try to change the page formatting, it does so for only a single chapter of the whole book. Is there a way to quickly and easily change the page formatting across the whole document?

Did you use page styles? How are your chapters delimited one from another? How much does your document rely on ditrect formatting? Are there objects of specific classes (sections, frames, tables …) used that may contain relevant formatting? Someone trying to help you might need a bit more of inforamation.