This option is selected when you are creating a new customer.
(You can also import customers from a CSV file)
Go to Customer > Lookup and click on the Add New Customer button or select New Customer from the main menu.
Hover the mouse over the different fields on the form. If the cursor changes to a hand () , click to get more information.
Note: To force the use of cash, use the Suspended (for invoices) and Cash (for credit notes) in conjunction.
Edit Restricted (You can see the fields but you can't edit it).
Fields like Active, Cash client, Suspended, VAT type, Credit limit, Discount, Interest, etc. will display, but you won't be able to edit the fields.