(IQ Super User)
Many companies want to isolate a specific sales person to see only their own customers for multiple reasons. IQ allows you to do this within the User Settings.
First, you might want to consider restricting the user's position.
Open the users's account and scroll down to the ROLES/PERMISSIONS

Base Sales Limited is defined in the "positions" as follows:
In order to restrict the user's view of customers it is necessary to assign them to a specific customer:
Restricting to the First Customer:
Scroll down to the OTHER DETAILS
Choose a specific CUSTOMER and the correct FACTORY LOCATION
Adding Additional Customers
You will then need to add the additional customers assigned to them
Click on the ALTERNATE VIEWABLE CUSTOMER, select and add them
Allowing the user to see multiple customers
Make sure you clear the DEFAULT customer so that they can see all customers in the list.
The Result
With the settings above applied the user will only be able to see their own customer's quotes:
Also, they will only be able to see their own customer's jobs: