I understand that the SCALELISTEDITcommand is intended to establish a global list of scales instead of just dwg specific ones. The HELP says that the master (global) scale list is located in the User Preferences tab of the Options dialog box. When I type OPTIONS and see the User Preferences tab, I do not see any reference to the scale list.
Autodesk confirmed to me that the editable global default scale list was new for AutoCAD 2011, and it didn't make it into all of the AutoCAD vertical products (like Architecture 2011). That blurb in the Help was likely copied/pasted from the plain AutoCAD Help - hence the confusion and the ongoing frustration with Architecture's Help system (that's another rant entirely).
Autodesk said that the only way to edit the default list of scales used by AutoCAD Architecture is to manually edit the associated registry key, which is neither supported nor advisable.
Here we are in 2012 and still no such feature in Architecture 2012. Autodesk, please implement! Any echos to this sentiment?
Note You can modify the list of scales that are displayed in all view and plot scale lists with SCALELISTEDIT. After you add a new scale to the default scale list, you can use the Reset button in the Edit Drawing Scales dialog box to add the new scale to your drawing.
This is not true. If you change a scale using the SCALELISTEDIT, that only affects that drawing, and hitting the Reset button restores the default settings, wiping out the modifications you just made. You would have to make the changes in the Default Scale List Dialog Box to change the registry values, and then use the Reset button in the SCALELISTEDIT (Edit Drawing Scales) dialog. But you cannot do that in ACA....