Creating a suspense class
Configuration > Purchases > Classes > you can create a suspense class by checking the "suspense account" box and selecting all types for which you want to create suspense accounts (here Suppliers) :
Creating a suspense account
Configuration > Purchases > Accounts > you can create an account with the "Supplier" type and then select the previously created class (the suspense account field can't be modified).
Exactly the same procedure to create the Customer, Collected VAT, Staff, Costs, and Deductible VAT account types.
Note: it is only possible to create one suspense account by type.