My powerpoints contain several hundred slides each – I have joined lots of separate powerpoints into one big document with an index at the start so that I can click on the area I need each lesson and hyperlink straight to the slide I want. Since the individual powerpoints are a mixture of styles, fonts and animations, I use macros to loop through all the slides and make the same changes to every slide with one click.
Macros are different in powerpoint from in Word since the macro lives in the individual powerpoint document and not in the Normal template. I therefore have a dummy powerpoint document containing every macro I have made; I make sure that when I want to use a macro on a powerpoint document I have the dummy document open in order to pick the macros from it. Developer has to be on the toolbar as described here.
When I click on the Macros button I can select a macro from my PowerpointMacros master document which I can then use in any other powerpoint:
Chemistry Word VBA macros 