Harry wants to change the background of all of his presentation slides. which slide will enable him to make this change to all the slides at once?

Harry needs to change the theme to change the background of all his presentation slides.

Explanation:

To change themes in powerpoint follow these steps: first, click on the Design tab  and then select one theme from the options .

Notice that themes also change the position, font, color and size of the text,  among others.

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