You change or remove a theme by making a selection from the gallery on the Design tab in PowerPoint. Select a heading below to open it and see the detailed instructions. Change the current theme On the Design tab, in the Themes group, click the More button (illustrated below) to open the entire gallery of themes: Do one of the following: To apply a built-in theme, under Office or Built-In , click the theme that you want. To apply a newly-created theme or an existing theme that you previously modified and saved, under Custom , click the theme that you want. ...