Hi TL,
If you want to change the default color (Blue) of the Hyperlink in PowerPoint. The PowerPoint I use is 2007 version.
Run PowerPoint, Go to "Design" > "Colors", there are many built-in themes in the pull-down menu such as "Grayscale","Apex", "Aspect" and so on. You could select one theme from them directly.
Or you could click "Create new theme colors" in the pull-down menu to set a color by yourself. Go to "Hyperlink" and set up the color of the hyperlink. Click "Save" to save your settings.
Hope it helps!
Claire