US dollars are accepted in some of the places in Bora Bora but you'll get a low rate of exchange so it's best to exchange your US Currency for Bora Bora dollars to get a better exchange rate on your money.
You can also use your credit or debit cards at ATM machines around Bora Bora and get currency that is more widely accepted in Bora Bora.
Or the hotels and resorts and places you eat at should also accept your credit or debit card.