To modify a custom dictionary:
Select Tools > Options from the menu bar. The Options dialog box is displayed.
Select Editor > Spelling from the navigation tree. The Spelling settings are displayed on the right.
Click Custom Dictionaries to display the Custom Dictionaries dialog box.
Select the custom dictionary to edit, and click Modify to display the [Custom Dictionary Name].dic dialog box.
Make any necessary changes.
Click OK until you have exited the Options dialog box.