Hello Alicia26,
Welcome to the Community page,
So it would be a case of having to go into each one to change them there is no way to bulk change the, However you could purge the account and start again but this would mean you would loos any data that has been entered in already like invoices just to make you aware.
If you are wanting to purge the account to start again you will need to ring the support line on 0808 234 5337 it is open mon to fri 8-7 and they will be able to raise this up and get it done for you.
Also just to let you know when your in the new account and you re import them in check the import of the csv file is the same as out sample test one so that the same thing doesn't happen again to you.