To be able to edit a menu that was already created, go to Edit -> Preferences.
In the Hidden Elements section, make sure to check Scripts.
Next to the menu, you will see a script shield icon, select this to bring up the edit dialog box in the property inspector.
NOTE:
When moving the site from one computer to the other, the page the menu was applied to and the CSSMenuWriter folder will need to be added into the Dreamweaver site in the same location relative to the site root as on the original computer.
For example, say you create a site on the PC with the following path as the root:
c:\websites\testSite
and the page you apply the menu to is at:
c:\websites\testSite\testfolder\page.htm
The CSSMenuWriter folder will be created at:
c:\websites\testSite\CSSMenuWriter.
When you move the site to the Mac, you must maintain the same relationship. So if you create the site on your Mac with the root of:
mac harddrive: websites: testSite:
The CSS MEnu Writwer folder will need to be at:
mac harddrive: websites: testSite: CSSMenuWriter
and the page you applied the menu to will need to be at:
mac harddrive: websites: testSite: testfolder: page.htm