Can I change from an APEC card entry to a Non-O retirement visa in Thailand?

can't find anything that says you can't. If an APEC entry is considered a '"tourist entry", you probably can

Honestly I don't know if you can go from a 90 day APEC card entry to an in country Non-Immigrant type visa and I would imagine you'd have to go to your immigration office and see what they say.

IF I was a betting man I'd bet they say no, you'd have to exit/re-enter on a "normal" entry stamp of your nationality not a special entry like APEC is

BUT

as I said I don't know, let's see if anyone replies back to your post