The Control Level determines a user's level of access to the Control Centre.
The standard level of control is Setup Wizard which will only allow the user access to pages which are essential for configuring Transactor for your dental laboratory. You should progress through the pages of the Setup Wizard when setting up Transactor for your lab for the first time, as this will allow you to enter your company details, customers and prices, amongst other important things.
The Advanced level is only available to users who have been given this access level, and allows control over the more advanced features of Transactor, such as custom fields, nominal accounts and customisation of reports.
Users can be configured with different levels of control, allowing them access to just the Setup Wizard, or the Setup Wizard and Advanced pages. Each control level gives the user access to that control level and below - so an Advanced user will have access to the Advanced and Setup Wizard pages of the Control Centre.