Changing the base theme automatically changes the theme of all pages to which the base theme is currently assigned.
In the Web Site drawer, click the Themes tab.
Click Replace in the Current Base Theme field. A new window displays the Select Theme screen.
Click the radio button next to the theme you want to use as the base theme.
Click Apply. The Select Theme screen closes.
The selected theme is displayed as the current base theme.
Replacing all themes with the base theme replaces all themes applied to individual pages with the current base theme.
In the Web Site drawer, click the Themes tab.
Click Replace All With Base in the Current Base Theme field.