To change the text fonts, colors, or general look of objects in all worksheets of your workbook quickly, try switching to another theme or customizing a theme to meet your needs. If you like a specific theme, you can make it the default for all new workbooks.
To switch to another theme, click Page Layout > Themes, and pick the one you want.
To customize that theme, you can change its colors, fonts, and effects as needed, save them with the current theme, and make it the default theme for all new workbooks if you want.
Picking a different theme color palette or changing its colors will affect the available colors in the color picker and the colors you've used in your workbook.
To add your own color, click More Colors, and then pick a color on the Standard tab or enter numbers on the Custom tab.
Tip: In the Sample box, you get a preview of the changes you made. Tip: You can click Reset before you click Save if you want to return to the original colors.Picking a different theme font lets you change your text at once. For this to work, make sure Body and Heading fonts are used to format your text.
Picking a different set of effects changes the look of the objects you used in your worksheet by applying different types of borders and visual effects like shading and shadows.
After making changes to your theme, you can save it to use it again.
Note: The theme is saved as a theme file (.thmx) in the Document Themes folder on your local drive and is automatically added to the list of custom themes that appear when you click Themes.
To use your custom theme for all new workbooks, apply it to a blank workbook and then save it as a template named Book.xltx in the XLStart folder (typically C:\Users\user name\AppData\Local\Microsoft\Excel\XLStart).
To set up Excel so it automatically opens a new workbook that uses Book.xltx:
Tip: Pressing Ctrl+N will also create a new workbook that uses Book.xltx.
