Set document margins and orientation

The client asked for landscape orientation for the appendix and standard portrait for the rest. Change only pages 10 through 14 to landscape, set margins to 0.5 inches on those pages, keep the header with the document title aligned, and verify page numbering continuity.

Before I send the proposal to legal, make the margins and orientation clear for reviewers. Put a one-line note in the header on pages that switch to landscape, set portrait body pages to 1-inch margins, landscape appendix to 0.5-inch margins, and flag any tables that exceed the new widths.

I changed orientation for the appendix but discovered the entire document switched to landscape. Legal will reject a file that disrupts page flow. I am not sure whether I applied the change to a section or the whole doc. What likely step did I miss, and what is the fastest way to fix only pages 10–14 without altering headers and page numbers?

Every round of client revisions causes me to reapply landscape sections and tweak margins; this wastes an hour per revision and introduces header mistakes. Across dozens of proposals, where am I losing time and credibility, and what two habits will prevent orientation and margin regressions before each delivery?