How can I prove that my savings for a NON-O visa extension in Thailand came from overseas?

The user is seeking advice on how to demonstrate that their savings, necessary for extending their Non-O visa, are from overseas. They express concerns about transferring funds into a Thai bank account within a month of opening it and ask if bringing cash is a viable option. The community responds by clarifying that cash cannot be brought in for this purpose and that funds must be shown as foreign transfers through a bank. They also mention that the money needs to be in the Thai bank account for at least two months before applying for the extension.