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 users with this level will be able to access that content.

An Access Level has two Default Access modes that can be changed from the Options tab:

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

Read more about Access Level Options here