I am using QBO Simple start.  Somehow an expense transaction was assigned to Customer A.  I want the transaction assigned to Customer B.  In this version you can not see the customer anywhere on the expense screen.  Occasionally you can change the payee and it will move the transaction however that is not working today.  You can see Company B in the payee fields of the expense, when you run the profitability by customer the transaction is assigned to Customer A.  

I have used the  Accounting Tools under the accountant log in to reclassify the transaction.  This screen will show the customer/vendor as Company B.