How can I change my Non-O visa to a Non-B visa in Thailand?

Your embassy actually has nothing at all to do with Thai visa and extension requirements and how they are processed. The big thing is you first have to have a job that can meet the qualifications to get your work permit, as you can not work without one, meaning you can't get a type B visa extension. If it is not a BOI registered company, then for each work permit for a foreigners they must have at least bt2million in registered capital with their business, and four paid Thai employees, and this applies to Thai companies also, except for teaching in a registered school, that is the only exception. You do not get a type B visa/extension without first having a job.

If you fly out of Thailand be prepared to do Thailand Pass (TP) all over again

Non-O for what reason?

Pretty sure you'll need to fly out and then come back, I was on a Non B and I had to fly out over new year so that I could apply for the Non O

You might not need to change it. You can change the reason for your extention of stay as they're both Non Imm visas.

What does your employer say about it?

Fly out and come back with non visa or tourist visa