Select “Users” from the left side Menu and select “Catalog Users” from “User” menu
Under “Users List” section, you see the details of catalog users as shown in the image below
Choose the user from the list and click on the pencil icon to edit the details and the “Edit Catalog Users” dialog box will pop up
Click on the “Member Group” field to assign the user to a group
Select the relevant group from the group list and click on "Save" button to save the changes