When editing the footer on a slide master, its child layouts automatically inherit the footer text. However, after accidentally editing a layout, they are not in sync anymore. I always have to edit the text on the slide master and some layouts separately.
How can I make the layouts inherit the slide master footer text automatically again?
MS changed the way headers/footers/page numbers etc. work in PPT 2007; they're now treated as shapes on the slide where they appear, rather than as true master shapes. There are upsides and downsides to this. I suspect you're stuck on the downside.
If I'm correct about the cause, you'll need to select and delete the footers/etc on the affected slides, then choose Insert | Header&Footer and put checks next to the items you want on the slide.
I had the same problem. To fix, I duplicated the layout that I wanted to use, applied that layout to the slides where I needed the footer (for me this was all slide except the title slide). Then I added the footer from the insert menu and selected apply to all slides. I don't know why it would not do that from my original layout but it worked fine from the duplicated layout.
In Office 365, I find that this procedure works:
You must repeat one master slide at a time. At least at the time of this post, if you select multiple slides and repeat the disable/enable step above, then the new footers are only copied to the first child master slide selected. So you still need to click one slide at a time, but at least no need to cut-and-paste.
