Note: Premium subscribers can simply edit and download their design at any time via the My Stuff page.
Users of a free basic account of PosterMyWall will have to regenerate the design they want to modify after purchase, because the version of the design downloaded is the one made at the time of purchase.
You can regenerate the downloadable file by using a courtesy edit. Go to your Order History and select 'Make a Correction'.
The design will open in the editor. 'Click Save and Recreate' once done. Access the new file via the emailed link or your Order History.