memorized transactions

That is how QB Desktop works.  I assume it is because it would be unusual for the reference (invoice #) number to be the same for next month's bill as it was for last month's bill, for example.  It would be nice to have that option though.  Utility bills are ones that would be nice to have the reference number carry forward.  However, you can include a memo on a memorized bill transaction and that will carry forward.

I believe if you set up the vendor to add the account number it will do it for you, go to vendor edit payment settings and put account number in there