What are the requirements for a year extension for over 50 expats in Bangkok with a Non-Immigrant O visa?

hi, I wanted to have information about a year extension for over 50 in Bangkok. I arrived Thailand with a non-immigrant-o single entry. in 45 days I will go to request the extension. in the bank I have to ask only the document that certifies that the money has been on the account for at least 60 days or there are other documents to request? and the extension will start from the expiration of the non-immigrant-o single entry or from the date of my arrival in Thailand? thanks for the help