by AJ George 
Ever received a PowerPoint presentation from someone and wished you could apply your own, previously created master slides in the presentation? Easy peasy; here's how:
- Open both the recipient and the source presentation (the source presentation is the one that has the master slide you would like to use in the recipient presentation).
- From within the source presentation, choose View > Master Views > Slide Master.
- In the slide thumbnail pane on the left, right-click the master slide that you would like to copy. (Selecting the larger slide master at the top will automatically select all of its associated layouts. To copy just one layout, you would right-click and copy just that master slide.)
- Choose View > Window > Switch Windows and select the recipient presentation.
- In the recipient presentation, choose View > Master Views > Slide Master.
- If there is not already a customized slide master in the recipient presentation, right-click one of the blank slides and choose Paste (or press [Ctrl] [v]).
- If the recipient presentation already contains customized slide masters, right-click below the last customized slide. You can select either Use the Destination Theme (the first image below) to use the theme of the current presentation; or Paste Keeping the Source Formatting (the second image below) so the pasted master will have the theme of the source presentation.
- When you are finished, choose Slide Master > Close > Close Master View.