I created a short video explaining the new custom themes:

• 0:00 Quick demo of the new feature in the watch app and in the phone app
• 0:26 Making a composite theme on the watch
• 1:49 Creating a new custom theme
• 2:19 Recalling, deleting, undoing themes
• 3:00 Using custom themes in the phone app
• 3:33 Deleting a theme in the phone app
• 3:38 Sharing themes via Share-code
• 3:51 Using a Share-code
• 4:09 Sharing themes via Bubble Cloud Rich-image
• 4:27 Using a Bubble Cloud Rich-image
• 4:36 Making a custom watch face by importing image components
• 5:35 Sharing a theme with custom components
• 6:49 Custom theme examples

For more information on the custom themes see this post: Version 9.65: Create / share your own themes