Apply a different background to an individual slide

If you added a common picture background to the master or to an individual slide layout you still can change that on an individual slide.

Just use the procedure I described in my previous blog post:
Right click your slide -  choose Format background - Picture or texture fill - File - browse and select your image - click Insert. Be sure to click Close and not Apply to all.

To reset it to the master, right click the slide, choose Format background, then click the Reset background button and click Close, not Apply to all.