I added a Level to a user, but it can still see other content?

When you create an Access Level to restrict some content, only members of this level will be able to visit the pages for that content.

Access Levels have a “Deny Access to Unprotected Content” setting that can be changed from the Options tab:

1. Enabled (default): Members can also access all content that has not been restricted by other levels
2. Disabled: Members can only access the content that has been restricted for this level

Read more about Access Level Options here