I renewed my Belgium passport 2 years ago from the Belgium embassy in Bangkok. When I pick up my new passport the Belgian Embassy gave me a letter to give to Thai Immigration which stated the reason for issuance of the new passport. Take your new and old passport to immigration and they will do what is necessary.
In Pattaya the bank letter was valid for three business days. Don’t forget photocopies of all pages in your bank book and have each photocopy signed. As stated before make sure you bank book (passport) is updated the same day you go to immigration.
I use Bangkok Bank. Any transactions I want to do at my bank I have to show both bank passport and passport. You have to show your bank passport and copies when you renew your retirement visa. To set up mobile banking on your phone you need to show these. Setting up automatic debit from your account for paying utilities. These are just a few examples
A bank password is what the banks call it. In western banks they called it a bank book which you updated at your bank either by a teller or ATM. Most banks in western countries do not use them any more. However here in Thailand it is much more important. If it is lost or stolen the bank will require you report to police in order for you to get a new bank passport. You will have to have with you for almost all transactions you make at the bank along with the passport from your country. I was at Bangkok Bank the other day and I was told I needed a new passport because mine was on its last page. You would not believe how much paperwork I had to sign in order to get a new bank passport
I renewed my Belgian passport at the Belgium embassy in Bangkok. The embassy gave me a letter to give to immigration which stated the reason for a new passport being issued.
As previously stated your Bank passport is linked to your passport from your country. Take your new passport to your bank to update the information.
Read previous comment from Brandon If you qualify for visa exempt then you have 30 days each time you enter. If you nationality is such that you need a visa then you are correct