Replace Box: This option will enable the Replace Box. This button will be added to row three of the visual editor. Usage: Placing a check in the box will enable the button in your visual editor. Unchecking the box removes the button from the editor. Yes, this button functions the exact same as the Search (Find) button. Seems kind of redundant to me... Highlight your text, and click the button. You can also click the "Replace" tab, for even more options.