. If it's a lump sum , I would use bank to bank using swift code. Multiple smaller amounts use other things like wise, remit, etc. You don't actually need to show international transfer evidence for 400k for spouse visa/ext. They don't care where it comes from. Cheapest way is in your pocket when you fly in, but exchange currency in Thailand, not outside . Better rate.
I got one of the last multi entries there last year 29th May. They stopped them 3 days later. 400k was still required . All e visa now and 3 month maximum.
. Yeah unfortunately too late. Same applies in most countries. I got 11 months extension of my visa here instead of 12 months because of my passport expiry. Most countries give new passport number when renewing now for security reasons. Visa is linked to passport number and valid for the length of passport life .