Nominee directors are NOT signatories on your bank account.  The only signatory will be you.  You can contact the bank directly after your account is open and verify you are the only signatory on the account.  In Panama the bank must contact and get approval from the existing signatories before it can add another signatory.  That means a new signatory cannot secretly be added to your account.

In addition, the banks know the nominee directors because they open accounts with their names as directors on a daily basis.  The bank would know something is wrong if a nominee were to start trying to get access to these accounts.  The banks understand what is going on and protect their clients because in Panama banks can be sued.

This problem has never happened to our knowledge in all they years we have been opening bank accounts for our clients.