Go to the publishers site or AppSore and update it.
Or run through this list of fixes
It's NOT advised to do any online banking in amounts your not willing to risk losing.
Any losses that occur involving a hacked machine is not going to be covered by the bank.
Keep your more substancial funds in a offline, off ATM, off overdraft, off everything savings account, then visit the bank regularly and transfer from the more secure account to the lesser online ones.