hcmc asked me the same.. I took all the pictures, merged, compressed and uploaded without problems. Now pending approval since 2 days. Fingers crossed I get approved after the weekend.
I have my residency for New Zealand and they transfer it to new passport. I am sure that Thailand will do the same. Otherwise as others have said, keep old passport and show that.
Ah okay, that could explain it. But, there have been a few mentions also from people applying in HCMC who seem to have entered unemployed and still were asked to supply proof of income.
nevertheless, I've been told that when applying for the soft power with seminar through Spain, they deny the visa. When applying from a different country, they grant the visa.