How to update the theme?

Just install the new version as regular theme (without demo installation). 

1. Go to Appearance → Themes → Add New.
2. Upload the zip file of the latest version of your current theme. For example, you can update the Twenty Twenty-Two theme by uploading a new copy downloaded from WordPress.org.
3. Click Replace active with uploaded when prompted.

Feel free to ask for support if it’s not clear!