To edit a Security Group, use the File tab→Security→Security Group Definitions command, and either double-click on the group, or select the group and click the Modify button. That will bring up the Security Group Definition dialog, where you can then modify the groups permissions.

 

Permissions are only applied when the user logs in. If a user’s permissions change while they are logged in, the new permissions will only be effective after the user logs out and in again.

 

Please note that the Administrator security group can not be modified.