Can I switch from an expired Non-B visa to a spouse visa in Thailand?

"My Non-B visa has unfortunately already expired", so what stay are you currently on?

this is the choice you'd want if you are going to a thai consulate in a nearby country to apply for the 90 day Non-O visa based on 'trailing spouse' (married to a foreigner who legally works here)

𝗛𝗮𝘀 𝗮𝗻𝘆𝗼𝗻𝗲 𝗵𝗲𝗿𝗲 𝘀𝘂𝗰𝗰𝗲𝘀𝘀𝗳𝘂𝗹𝗹𝘆 𝘀𝘄𝗶𝘁𝗰𝗵𝗲𝗱 𝗳𝗿𝗼𝗺 𝗮𝗻 𝗲𝘅𝗽𝗶𝗿𝗲𝗱 𝗡𝗼𝗻-𝗕 𝘃𝗶𝘀𝗮 𝘁𝗼 𝗮 𝘀𝗽𝗼𝘂𝘀𝗲/𝗱𝗲𝗽𝗲𝗻𝗱𝗲𝗻𝘁 𝘃𝗶𝘀𝗮 𝗯𝗲𝗳𝗼𝗿𝗲?

NOPE, it cannot be done, :( Once you have an expired/cancelled visa/extension you cannot change the category anymore..

𝗗𝗶𝗱 𝘆𝗼𝘂 𝗻𝗲𝗲𝗱 𝘁𝗼 𝗲𝘅𝗶𝘁 𝗧𝗵𝗮𝗶𝗹𝗮𝗻𝗱 𝗳𝗶𝗿𝘀𝘁, 𝗲𝗻𝘁𝗲𝗿 𝗮𝘀 𝗮 𝘁𝗼𝘂𝗿𝗶𝘀𝘁 ? 𝗢𝗿 𝗮𝗽𝗽𝗹𝘆 𝗶𝗻𝗱𝗲𝗽𝗲𝗻𝗱𝗲𝗻𝘁 𝘃𝗶𝘀𝗮 𝗼𝘂𝘁𝘀𝗶𝗱𝗲 𝗯𝗲𝗳𝗼𝗿𝗲 𝗿𝗲-𝗲𝗻𝘁𝗲𝗿𝗶𝗻𝗴 𝗯𝗮𝗰𝗸?

You can do either, leave/come back and apply for the initial 90 day Non-O visa based on spouse of a foreigner who legally works here OR go to a nearby country and apply online for the 90 day Non-O visa for that reason, then wait in that country until the application is processed.

* 𝗗𝗼𝗲𝘀 𝘁𝗵𝗲 𝗳𝗼𝗿𝗲𝗶𝗴𝗻 𝗺𝗮𝗿𝗿𝗶𝗮𝗴𝗲 𝗰𝗲𝗿𝘁𝗶𝗳𝗶𝗰𝗮𝘁𝗲 𝗻𝗲𝗲𝗱 𝘁𝗼 𝗯𝗲 𝘁𝗿𝗮𝗻𝘀𝗹𝗮𝘁𝗲𝗱 𝗶𝗻𝘁𝗼 𝗧𝗵𝗮𝗶?

* 𝗗𝗼𝗲𝘀 𝗶𝘁 𝗻𝗲𝗲𝗱 𝗹𝗲𝗴𝗮𝗹𝗶𝘇𝗮𝘁𝗶𝗼𝗻/𝗮𝘂𝘁𝗵𝗲𝗻𝘁𝗶𝗰𝗮𝘁𝗶𝗼𝗻 𝗳𝗿𝗼𝗺 𝘁𝗵𝗲 𝗲𝗺𝗯𝗮𝘀𝘀𝘆 𝗮𝗻𝗱 𝗧𝗵𝗮𝗶 𝗠𝗙𝗔 𝗯𝗲𝗳𝗼𝗿𝗲 𝗮𝗽𝗽𝗹𝘆𝗶𝗻𝗴?

As a rule most immigration offices require that the foreign marriage certificate be legalized by your embassy here (and some embassies no longer do this service meaning you get the legalization back in the country you were married in instead), then have that translated into thai, and have that translation certified by the MFA office

Unfortunately Most of the stuff you're asking are questions you need to talk to your husbands employer about (because they have to issue you support documentation to get the initial 90 day Non-O visa). Plus remember that an employer is not obligated to do that <- some employers won't provide documentation for trailing spouse to get the visa/extensions :/

AND

You should go to the immigration office where your husband works/lives to check with them IF you can get the in country Non-O visa issued (once you come back in visa exempt entry) because not all offices can issue in country Non-Imm visas. If they can't do it then you'd have to go to a nearby country and apply online thru the thai consulate there

Also while you're there at your immigration office get the requirements from them as far as the matching extension based on "spouse of a foreigner legally working here" because it's a pile of paperwork :O