You can change
column and margin settings for pages and spreads. When you change
the column and margin settings on a master page, you change the setting
for all pages to which the master is applied. Changing the columns
and margins of regular pages affects only those pages selected in
the Pages panel.
Note: The Margins And Columns dialog box doesn’t
alter columns inside text frames. Text frame columns exist only
within individual text frames, not on the page itself. You can set
up columns within individual text frames by using the Text Frame
Options dialog box. Text frame columns can also be affected by the
Layout Adjustment feature.