If you need to exchange THB, find the SuperRich shops outside of the airport (a few levels below, near the airport train) and in town - they are everywhere and decent rates
But most places take credit card, Alipay + and PromptPay (linked to the Octopus), good rates too.
For Alipay+, you can download, purchase at a very small cost, numerous discount vouchers that can be used on payment, pretty sweet deal.