Rotas do not have a lot of settings however their is one Setting available which can be located within: 

Administration > Company > Settings > Time Tracking Settings.

Rotas can be set to look at the Entire Organisation or by department, department access will show all employees who are in the Managers Department and therefore they can only built Rotas for these specific Employees.

If the setting is set to No then Managers will see all available employees company wide.