I’m living in Thailand and using my superannuation savings. Do I only have to pay Thai tax on the earnings from the fund, rather than the whole amount I withdraw? For instance, I withdraw $6,000 a month and the fund earns about 11%.

Superannuation is classed as pension income. I have a video explainer video for the Australian / Thai Double Taxation agreement. Here is the video https://youtu.be/y1chBfp8_XE

If you withdraw and remit (transfer to Thailand) AUD6,000 per month, then AUD72k (1.7m THB) is assessable income.

You can deduct off your allowances and deductions, then you will follow the Thai tax tables.