If the PowerPoint Themes gallery doesn’t contain the theme you want, you can borrow a theme from another PowerPoint presentation. To recycle a PowerPoint theme from another presentation, follow these steps:
On the Design tab, open the Themes gallery.
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The Themes drop-down list opens.
Click Browse for Themes.
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Choose Theme or Themed Document dialog box.
Locate and select a PowerPoint presentation with a theme you can appropriate for your presentation.
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You may have to browse to find the presentation you want to use.
(Optional) Examine the themes.
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Click the Views button in the upper-right corner of the dialog box and choose Preview.
Click the Apply button.
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The theme used in the presentation you selected now inhabits your presentation.