This article will explain how to change your button theme, adjust the buttons, or even supply your own buttons!
Visit the button theme area of the theme under Themes > [ThemeName] and clicking on Buttons & Graphics on the left menu. Here you can choose from existing button themes or modify the existing ones.
Changing the Graphic Files
To modify the existing buttons, there is a download button that will zip the images into one file and export them to your computer. After the download is complete, unzip the graphics and edit the desired buttons in a graphics program. Create a "Buttons" folder on the FTP under your site's root folder (/storename/www/Buttons). Inside that folder, make another folder with the name of your button set, like BlueButtons. Upload all of the new button files to that folder then select that set from the Theme Manager.
Steps for multiple store fronts:
The same steps as above must be followed for each of your multiple storefronts. There must be a Buttons folder with a subfolder of the theme name for that button set.
Upload your new buttons to:
“StoreNameOne/www/Buttons/StoreNameOne - BlueButtons /” “StoreNameTwo/www/Buttons/StoreNameTwo- BlueButtons /”
You can now login and change your active button theme for these two stores.
Changing your active button theme:
Select Theme from you to your drop-down menu. Go to the left menu and click on 
Buttons & Graphics under 
Theme Settings. Select the button theme you wish to use and clicke the Update button. This will select your button theme and save it as the active theme for your site. Buttons & Graphics” . From the drop down on this page select the button theme you wish to use and the click the “Update” button. This selects this button theme to be the active theme for your site.