Only Workspace Admins can assign the Workspace Admin role to other members of the workspace.
Click the task panel entry Members.
In the line of the member, open the dropdown list Workspace Role and select Admin.
If you want to change more than one member at the same time:
3. Hover the mouse pointer over a member and mark the checkbox at the beginning of the line.
4. Repeat the above step.
5. Open the Change Role dropdown list at the top.
6. Select entry Admin.