@Frangipani ******
with an overstay history, you indeed cannot apply on Thai Immigration for the "change of visa type" from a touristic entry to a 90-days Non-Imm-O visa . . . . . However, you are still able to apply for the Non-Imm-O visa in your home country. An overstay history is irrelevant to the Thai Embassy or Consulate in your home country