Hello, I want to make a 400 page text book. How can I select each page's text frame in one shot and change their size simultaneusly? (each text frame has same size per page)
Make a backup copy of the file incase something goes wrong, then:
Make sure the frames snap to the margins on all sides -- change the margins on the applied master page to achieve this, if necessary.
Enable Layout Adjustment (Layout > Layout Adjustment...)
On the master page change the margins to be the size you want the new text frame dimensions to be.
If, for some strange reason, you don't want to use these margin settings in the layout, turn OFF layout adjustment and reset them on the master page again to what you want.
Thank you! That works!