How to: Edit footers in master placeholder.
Solution:
Type the desired footer in the 'Footer Area' placeholder , in 'Slide Master' view.
1) Move to 'Slide Master' view:
a) Select the 'View' menu and select 'Master'. (The Master submenu appears.)
b) Select 'Slide Master'. (The Slide Master slide appears.)
2) Select the 'Footer Area' placeholder . (Handles appear around the selection box.)
Footer Area placeholder
3) Type the desired footer text.
4) Move the 'Footer Area' placeholder to the desired location.
5) Click on a blank area to deselect the placeholder.
6) To return to slide view, select the 'View' menu and select 'Slides'.