Hi Michael,

For your first question, go to Accounting > Configuration > Journals and look at the sequence of the journal items listed. The topmost "liquidity" type of journal (i.e., Bank or Cash) would be the default one used when triggering payment. Just drag your preferred default bank journal as the very first liquidity journal item (not necessarily the very first journal item in the list).

On your second question, I'm assuming you haven't tagged the bank account as trusted. If you're referring to your own bank account(s), go to the bank journal you had set up for this, and on the "Bank Account Number" field, select the right arrow:

Then from the following screen, toggle the "Send Money" indicator to green:

It should now be marked as "Trusted" in the system now. For vendor bank accounts, when you do the process of paying, you can do similar approach above, but make sure the bank account is really trusted. See info: https://www.odoo.com/documentation/master/applications/finance/accounting/payments/trusted_accounts.html

I hope these are the answers you're looking for.