Get your taxes done using TurboTax

The opportunity to link a bank account for Business Expenses is a one-time link.  Try creating a new Business, and enter the initial setup info, then enter some income.  You could use your original business, just change the name a bit.  

Then when you indicate you're Done with Income, you should get a page titled 'Next Up, Claiming Your Expenses!' with a video. Continue, and on the next page you'll see a blue 'Connect My Accounts' button.

Once you're done with this business, you can delete the original business.

@alishahabi