I think there are two ways. On is to have a part of the money at the Thai account and a letter from your ambassy that proofs your retirement income.
The other way is to have one half of the money at the Thai account and to transfer the monthly income every month from your hometown bank to the Thai bank but I think this has to be done for at least one year.
This lady was asksking about bringing medicines. So if she got Medizin from the list she needs a letter from her doctor. Rules are that she can only bring for one month even with the letter after this she has to buy the medizin in Thailand. I think there is no other way around.