I have created a master powerpoint presentation, where themes are chosen in master so people using it can pick and choose between several backgrounds within our profile. The problem is when a slide is copied and pasted somewhere else in the file - and you choose one of the themes in master to change the background - it then changes the theme/background for all the above slides. This does not happen if you add a new slide and choose a theme for this slide only. Just don't understand why this is happening - and hope someone can help

I do not use powerpoint often