@sw1222 

The answer depends on:

1) Is the external account a business account or a personal account?

2) Why is this external account not in your QB company file?

Regarding #1, presumably this is a business account.  If it's personal, then the payment should be assigned to the appropriate equity account for the PLLC.  If it's a single-member PLLC, then Owner's Capital.  If the PLLC has made an entity classification election, then use the equity account that applies to the entity (S-Corp, C-Corp, etc.).

Regarding #2, is the bank account on another related-company's balance sheet or ???  The issue is that you have assets (this external bank account) for the firm that are not in QB and, therefore, the source of the bank account balance is also not in QB.  So, how is that bank account balance increasing if you're not tracking that in QB?  If you're not tracking this account elsewhere, then your balance sheet (and most likely your P&L) aren't accurate so just create a fake bank account called "External Bank Account" or something similar and assign that to the payments, it really doesn't matter.  However, if you're tracking this bank account elsewhere (in another QB file/company) then the payments should be assigned to a corresponding account with this other company.  

@FishingForAnswers 

I thought your response was good and didn't want to step on your toes.