@Edward *****
IF you want to apply for a visa at a Thai Immigration Office, the money needs to be in a Thai bank account on your name.
800.000 Thb if it is based on being over 50 years of age (populair retirement and deposit must come from abroad)
OR
400.000 Thb if it is based on marriage with a Thai citizen.
For the 1 year Extension of Stay it is:
65.000 Thb a month with foreign deposit into a Thai bank account in your name
OR
40.000 Thb a month into a Thai bank account in your name
ONLY if you want to use bank accounts with multiple names, you simply multiply mentioned numbers with the account holders.