I had issues trying to get credentials changed in Remote Desktop Connection Manager after my password expired on the servers in a group. I was trying to get to it by doing:
- Right-click the group name | Select "Properties"
 - Go to Login Credentials
 - You'll see that the options are disabled
 
SOLUTION:
- Right click the root node of the left pane | Select "Properties"
 - Click on the "Profile Management" tab
 - Highlight the Profile you need to change | Click the "Edit" button
 - Make the necessary changes and click the "Save" button
 - Click "OK" to get out of the Properties dialog
 - Click "File" | Save or Save All
 
Hope this helps!  I know I'll need to come back and remember this in 75-90 days when the next password reset comes around.
