One of the first things people do after installing their Drupal 8 software is to change the default theme. If you do not want to use one of the default themes, you will need to upload one of your choice to your site. The instructions below will guide you on how to set another theme as the default for your site.
How to set a default theme in Drupal 8
- Log into your Drupal 8 administrative dashboard.
Select Menu from the top menu bar.
Next, click on Appearance from the secondary menu that appears.
This brings you to the list of themes you are able to select under the Enabled Themes. Find your desired theme and click on the Set default link to set replace the current theme. In our example, we selected the Red theme as our new theme. Below is a before and after shot of changing the Drupal 8 theme. In this example you can see the change was very dramatic.
Before After 
