In the Create New Theme Fonts box, under the Heading font and Body font boxes, pick the fonts you want. In the Name box, enter a name, and click Save. Theme effects include shadows, reflections, lines, fills, and more. While you cannot create your own set of theme effects, you can choose a set of effects that work for your document. On the Page Layout tab in Excel or the Design tab in Word, click Effects. Select the set of effects that you want to use. To change themes, simply pick a different theme from the Themes menu.
To return to the default theme, choose the Office theme. To remove theme formatting from just a portion of your document, select the portion you want to change and change any formatting you like, such as font style, font size, color, etc. Once you’ve made changes to your theme, you can save it to use again. Or you can make it the default for new documents. On the Page Layout tab in Excel or the Design tab in Word, click Themes > Save Current Theme.