Yes you do. Your bank account on GrabMerchant must be a VietinBank account, which is registered under the cash loan contract. Then, during the loan tenor, you aren't allowed to change the account number. It means that your income from Grab will go to the VietinBank account.
If your current bank account on GrabMerchant is not from VietinBank, you need a request to change payment information, please read more instructions below.
Please find the guideline of changing linked bank account here.
Notice: If your VietinBank account has frozen (due to no activity within 12 months), you need to make a transaction to re-activate the account while doing loan procedures.