You mean the Advanced Editor when creating a signature? That has nothing to
do with the email editor; that button opens your default HTML editor.
You can set this in Control Panel-> Internet Options

Signature
Robert Sparnaaij [MVP-Outlook]
Coauthor, Configuring Microsoft Outlook 2003
http://www.howto-outlook.com/
Outlook FAQ, HowTo, Downloads, Add-Ins and more
http://www.msoutlook.info/
Real World Questions, Real World Answers
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> In Outlook, Adobe GoLive pops up as advanced email editor despite box
> being
> checked to use Word to edit email messages. Any idea what's causing this
> and/or how to undo. Thanks. LL