The Design Checker shows you how to fix problems with your publication.
To fix problems automatically:

Click the arrow on the right of the item listed in the
Design Checker task pane.

If an automatic fix is available, click it and Publisher will do the indicated action.
Some checks make an automatic fix available to you. These fixes are typically simple choices about deleting an object, moving an object, or resizing an object. In many cases, the automatic fix may be sufficient. However, you have limited control over what Publisher does automatically to fix a problem.