If you are a consistent reader of my blog posts, you know what a Magento theme is as I’ve already talked about it. Earlier, I showed how to install a theme in Magento 2 and how to create child theme in Magento 2.
A quick recap, the theme in Magento 2 is what defines the appearance of the store in the backend as well as the frontend. Installing the theme in Magento 2 makes your store user-friendly and professional which helps to build your brand name. Also banner displayed in the frontend is not designed keeping in mind any custom theme designs. The solution to this issue is to override extension file in theme Magento 2.
Today, I’ll cover the topic to change theme in Magento 2. The steps shown here are in accordance with the latest version Magento 2.3.0
For example, you have the Magento Blank theme now as shown here:
Backend:

Frontend:

Steps to Change Theme in Magento 2:
1. Log in to Admin Panel
2. Navigate to Content > Design > Configuration
3. Click Edit theme
4. In Applied Theme dropdown, select the theme that you want to change to.

After you have followed these steps, you can check that the Luma theme is now applied:
Backend:

Frontend:

Your store got a new makeover! You can change the theme to any custom theme that you have installed using the above method.
You can also refer to the video tutorial to Change Theme in Magento 2 from our Magento 2 video tutorial series:
Thank you.