Click here to see an article on customizing the Connect widget using the Widget Builder.
The theme setup in Widget Builder is set to be reusable across all apps. This allows you to customise your different widgets or switch themes on the same widget across apps and gives you full control of what the Connect Widget should look like for the app.
Steps to update your Connect Widget with your changes on the Widget Builder
First, save save and publish your theme. :
Next navigate to the app with the keys for the Connect Widget you'd like your theme to appear on and click edit:
On the Edit App pop-up displayed, scroll to choose theme and select your theme from the list.
Finally select "Update app" and your Widget will be updated with your theme!