Can I convert my Non-B Visa to a Non-O Spouse Visa in Singapore, and what requirements do I need to meet?

An Australian with a Non-B Visa expiring on July 31, 2023, wants to convert to a Non-O Thai Spouse Visa. Questions include whether the conversion can be done in Singapore or must be in Australia, the format for a Thai spouse letter, and the acceptability of bank statements from two different banks showing over THB 400,000. Responses clarify that a Non-B Visa can be adjusted at expiration to reflect a marriage basis without needing a separate Non-O Visa application. Additionally, funds must be in a single Thai bank account for at least two months prior to applying.