@Dale *********
UNLESS you have a One Year Multiple Entry Non-O Visa based on marriage to a Thai National ( the one where you are stamped in for 90 days on arrival), you do not have a visa, but an extension of stay.
You can change the reason for the extension of stay of course, and it should be something your immigration office can do, but I doubt they would because you can work on your current extension of stay, and you’d submit the same documents as before to get a new extension of stay based on marriage to a Thai National