Editing of text is easier with the Search & Replace tool. It is available in the Text and Image editor that opens when you rollover some text on the page and press the wrench icon  on top left.

To find a word in the text - press the Search and Replace icon  . In the toolbar that opens to the right fill in the word you want to search for in the first field. Press the Search icon . The occurrences will be highlighted within the text.

You can refine the search by checking the Case sensitive option.

To replace a single word found in the text - fill in the new one in the Replace with field. Press the Replace icon  .

To change the word throughout the edited text, press the Replace All icon  .

To stop the Search and Replace preserving changes made so far - press Cancel  .

Press  UPDATE at the bottom of the editor to apply the changes on the page.