To change the background image in a section click on Background button on a section added in the website page.
Click on replace button. To replace the background Image and press remove button to remove the background image added.
Click on Save button.
Note : Doing Save and Publish Website changes without Saving Background Image Changes doesn't update the changes in your website and you might have to redo.
By Clicking on Light Text or Light Text Highlight or Theme Text will change the font color of the text with default text color or theme color.