Select the text or text box you want to edit.
Click the Font drop-down list on the Formatting toolbar.
Click a new font.
PowerPoint applies the new font to the text.
When you assign a slide layout to a slide, the layout includes a default font and size for the various text objects it includes. You can change the font and size of text as needed. For example, you can increase the size of your title text to make it more prominent.
Using the Font Dialog Box
Another way to change the font is to open the Font dialog box (open the Format menu and choose Font). From the Font dialog box, you can change the font style and size, and set any special effects, such as superscript text or embossing. Click OK to apply any changes.
To change the font size, click the Size drop-down list on the Formatting toolbar.
Click a new size.
PowerPoint applies the new size to the text.
Using the Toolbar Buttons
Another way to increase or decrease font sizes is to click the Increase Font Size or Decrease Font Size buttons on the Formatting toolbar. This allows you to change the size incrementally without knowing an exact size measurement.