Please read Blog Theme Retirement on glow Connect. As of January 2020 we removed some of the themes used in Glow as they are not compatible with newer versions of WordPress. They have already been removed from the Theme Picker Blogs that use these themes will revert to using TwentyFourteen on 30th January 2020 Please take action now.
We have some tips on Testing and Changing Themes which will help in planning your change.
You can change the way your blog appears and functions through Themes.
When you set up a new blog it has the theme TwentyFourteen applied as standard. Some themes are suitable for different purposes.
If you are switching themes you may lose any widgets you have set up. You can save the content of these widgets by dragging them to the Inactive Widgets section of the Widgets area of the dashboard before you change theme.
You may also have to place you menus after switching theme. Your menus will be the same but they will not appear on the blog until you set their location.
Themes can be managed via the Theme section of the dashboard or via the Customizer. We cover the dashboard method below.
Themes are managed from the Theme page of the Appearance section of the dashboard .
This page shows the current theme  and Thumbnails of all of the other themes. You can Preview each theme and activate them from the links under each thumbnail. clicking on the thumbnail will preview that theme.
Video: Themes on Blogging Bootcamp shows changing themes in an older version of Glow Blogs (some of the themes shown are not available).
Some examples of changing themes that may help:
Example of some themes.
Jetpack – Examples using the Jetpack Plugin The JetPack Blog uses the TwentyFifteen theme.
Make Theme The Make them supports a page builder when you select that from the template chooser for a page you can add various sections to your page: banners, column sections and galleries.
TwentySeventeen – An Example Glow Blog The TwentySeventeen theme supports Video headers, multiple sections on the front page as well as widgets, navigation and social menus, a logo, and more.
Example School Sites links to a few example blogs using different themes and different features of some of those themes.
If you need to customise your theme and are willing to learn or use CSS the Custom CSS page on the jetpack blog might help.