This what the requirements state. See: https://www.immigration.go.th/wp-content/uploads/2022/02/9.FOR-RETIREMENT-PURPOSES-50-YEARS-OLD-NON-O.pdf
"5.1 Present passbook and deposit certificate from banks in Thailand (in Thai language (Attention: Immigration Commissioner))
5.2 Copy of all entries of the applicant’s passbook showing that the applicant has a savings or fixed deposit account of not less than Baht 800,000 (all documents must be in the Applicant’s name)
5.3 Evidence of foreign currency fund transferred to Thailand"
5.1 is a letter form the bank confirming your account and the balance on the day it is written.
5.3 Is a credit advise confirming the funds came from abroad.