If you have connected QuickBooks to Taxomate, you will see the options to select bank and credit card accounts in the Payment settings step of Quick Setup ("Choose the accounts and customers for payments and fees"). It comes after the account and tax steps and before Review first payout.
IMPORTANT: Please connect your bank account to QuickBooks, where you receive your Amazon payments and pay Amazon fees. Also, if you pay your Amazon fees with your credit card, connect this account to QuickBooks.
Once you connect your accounts to QuickBooks, in Taxomate select the Payout bank account, the bank account where you receive Amazon payments.
Then select the Negative payout bank or credit card account, the bank or credit card account where you pay Amazon fees when your payout is negative.
You can change both later for each marketplace in Settings > Connections > Manage marketplace mappings.
For more advanced users, you can also consider using a clearing account and then transfer the balances to your bank or credit card accounts.