Re: We accept credit cards in payment of bills and we accept credit cards for retainers that go into a trust account. How can I direct the payment to the correct account?
That is correct. You can only have 1 bank account associated with your QuickBooks Payment account. What you can do is once the retainer payment posts to the bank account, do a transfer to your retainer bank account until it's time to bill the client from it.
As these are both asset accounts in QuickBooks, you can just record it as a Transfer in QuickBooks