There are a couple of different ways to format your text in PowerPoint presentation once you type it in. You can either use the menu bar or the Formatting toolbar. To format your text to change things like font, color, style, size etc. follow these steps: Select your text by either highlighting it or click on the diagonal lines that surround the text so that it turns to little dots. When you do this any formatting you add will effect everything in the box. Using the formatting toolbar choose the formatting that you want to add from the standard toolbar. There are buttons and drop downs for font, size, style, and alignment.
You can also go to Format on the menu bar and choose font. The font dialog box will open. Make your changes within the dialog box. Click OK and your changes will occur.