There are two types of custom words in Chinese Toolbox: words you've added and words you've changed. The current interface does not distinguish between these two. When a custom word is displayed in the Word Dictionary window, click the 'Remove customization' button to either remove the new word or revert it to what exists in cedict_ts.u8, the Word Dictionary source file.
To reverse ALL word customizations, quit Chinese Toolbox and delete CustomWords.dat (the custom words file) from your Chinese Toolbox document folder. To incorporate your custom words into another copy of Chinese Toolbox, copy the custom words file to the Chinese Toolbox folder on the other computer.
To complete this Tip, click on a custom word in the Reader to cause it to be displayed in the Word Dictionary window, then click the word dictionary 'Remove customization' button.