How Can I Apply for a Non-O Marriage Visa in Thailand?

You want THIS if you are applying for a yearly extension based on marriage

I asked because IF you are just applying for a yearly extension you want section L-1 (the one marked retirement)

BUT

IF you are applying for an in country 90 day Non-O visa based on marriage you want section C-1 and you need at least 15 days left on a 30 day visa exempt entry stamp, a 60 day tourist visa entry stamp, a 30 day regular extension from one of those OR a 60 day visit thai family extension from one of those. You CANNOT apply for a non-O visa in country from amnesty

Hang about ARE you applying for a yearly "extension of stay" <- as in you already had a non-O visa and want to apply for a yearly extension OR are you wanting to apply for the initial 90 day Non-O visa inside the country for the first time and have at least 15 days left on your current entry stamp or extension?

You want Visa Issuing Section C-1