Method A ADD USER
Menu > Employees > Employee Management > Employee List > Group > ADD USER
When ADD USER window prompts, find and select the employee you want to add.
The employee will be moved to the group.
Method B Changing from User Information
Method A ADD USER
Menu > Employees > Employee Management > Employee List > Group > employee > modify
Go to BASIC tab, use USER GROUP drop down menu to select the group. Press save after.
The employee will be moved to the group you selected.