Assign Customer role

Hi,
I am hiring SEO company to optimize my web site. They need to access back end admin panel. I don't want them to see my order information. Their work is to manage the web page contents of the web site. I tried to assign Content manager as their customer role. But it does not work. When I tried to log in with its username, it can do all things as I do as the web site global admin. How should I assign their role as the content manager only such as the web page, product description editting, etc.
Thanks.

Do they have all the permissions checked under Configuration -> Access Control List?  You should be able to clear them for their role to hide that stuff from them.