claim approval rules in trade management

On : 12.1.3 version, CLAIMS

claim approval in trade management

I am learning claims and deduction in trade management, according to the user guide, after creating and assign a claim, we must submit the claim for approval,then settle the claim and for approval again. But after i assign the claim and request for approval, the system requires to choose a payment method, and the system status is closed, after the approver approve, the claim closed, so it seems i just need to request approval once.
If the process above is not right, any setup i missed?