In this knowledge base article, you will know how to set up the Announcement bar in Blum theme. As you can see, you can customize the announcement bar by set up for these part:
This part lets you to select Accent scheme between Main accent and Extra accent color
You can enable or disable messages autoplay. After that, you can adjust the time to change the message: Range from 3 to 10s, with the default value at 5s.
To create new message, click on Add Messages. In order to change the content and add link, you can click on the message directly on the editor. By default, message link will be opened in new tab.