How to hide Save or Save As Button in Query Studio Toolbar

[mba]

Hello,
is there any possibility to hide or show the save- or save as-button in Cognos Query Studio based on user groups and roles. For example all administrators should have the possiblity to save the query. But as a normal user the save-buttons should be not available.

I know the possibility to hide user interface elements in Cognos Connection and Report Viewer by modifying the system.xml. But that doesn't work for Query Studio by modifying the toolbar.xml.

Any help would be great.

Thank you
Markus