Can I extend my 90-Day Non-O Visa in Thailand or must I exit and re-enter on a 30-day exemption?

I see clearly that you are confusing some things.

You cannot enter on a Non-Imm-O Family Visa and apply for the “1-year Extension of the Stay Permit” based on retirement

You cannot change the “reason” of the visa that you got issued. You will need to apply for the “1-year Extension of the Stay Per mit” based on being married to a Thai wife

*** you arrived on a 90-days Non-O Visa and got stamped in for a 90-days stay permit

*** you lost 3 weeks in the search of a bank willing to open an account for you, instead of using an agent service that would have opened an account for you within one or two days

***You do not apply for a “Retirement Visa”. You will apply for the “12-months Extension of Temporary Stay Permit based on being married to a Thai wife”. You do not have a visa any more

***you only need to show a minimum of 400,000 THB in your Thai bank account for the application to the 1-year Extension based on marriage to a Thai wife

***you need a freshly Thai Amphur printed Kor Ror 22 or 2 (whichever applies) marriage registry document to show Immigration that your marriage is acknowledged and registered in Thailand.

*** You don’t need 15 days left on a 90-days stay permit which you got when you entered Thailand on a Non-Imm-O Visa.

This requirement is only for those who apply for the “change of visa type” from a touristic entry to an initial 90-days Non-Imm-O Visa

You are able to apply for the “one-year Extension of the Temporary Stay Permit based on marriage” up from 30 days before the expiry of the 90-days stay permit.

***You gotta hurry up because the expiry of your 90-days stay permit is nearing. If you miss the date, you cannot get any 30 days extension on this

*** however what you can do, is applying for a 60-days Extension based on “Family visit” on Immigration before those 90-days stay permit expire

For these 60 extra days, you need a freshly Thai Amphur printed Kor Ror 22 or 2 (whichever applies) marriage registry document to show Immigration that your marriage is acknowledged and registered in Thailand.

***If you miss both deadlines or cannot prove your marriage inside Thailand (because it was never registered inside Thailand) you will face a problem.

*** However, there would still be a road open to achieve the 1-year Extension, based on RETIREMENT. For this, you must exit Thailand and invalidate the previous visa.

Then re-enter visa-exempt. You will get stamped in for 60 days.

Now you can visit Immigration and ask them for the application to the 90-days Non-Imm-O Retirement Visa inside Thailand (the “change of visa type”). For this application, you need a minimum of 15 days left on the 60-days stay permit. The application fee is 2000 THB

For this application, Immigration wants to see the minimum of 800,000 THB sitting in your Thai bank account. They also want to see a rental contract. There is no seasoning of the deposit needed at this point! Some Immigrations want to see a proof that the money came from abroad

***You will be issued the 90-days Non-Imm-O Retirement Visa “under consideration” for 14 days. After this period, you pick up the stamp at your Immigration.

***as soon as 30 days are left on the 90-days stay permit, and the bank certifies that the deposit has sat in your bank account for a minimum of 2 months, you can apply for the “1-year Extension of the Stay Permit based on Retirement”. The application fee is 1900 THB.

You can find the requirements to the “change of visa type” from a touristic entry to the 90-days Non-Imm-O Retirement Visa under number 9 on this Immigration website

I have given up on Thailand I've found a better place I'm over all the rules and regulations not my cup of tea anymore good luck everyone

Are you sure about the 15 days before? I also had my 2 months of 800k ready at the last minute and applied in bangkok on the day before the 90-day visa expired and there was no problem - other than being nervous it was the last day.

If, as you say, you are married to a Thai, you can get the 60 day "Visit Thai Family Extension" to give you more time (your wife has to accompany you when you make the application).

Go to the nearest immigration office, show them your passport and ask them.

What bank did you use

If you check the Thai government website for visa's. Unless they've changed again it's 3 months before your vias application and 3 months after.

Was the non O you bought based on marriage or being over 50? Because you can't change the reason till your second extension comes due.

What bank ?

This is a bit confusing. You mention marriage/family for the non O but then mention 800K which is the amount for a retirement extension. Marriage extensions require 400K

Which bank??

If you have a Non-O visa based on marriage you only need “seasoned” 400,000 THB . When you file for the extension the immigration office will give you about a four week extension counted from the day you show up at the immigration office. Within the first two weeks of that extension period you will receive a visit from immigration who will then send your file to the HQ in Chaeng Wattana and you will pick up your extension at your local immigration office. Important: any re-entry stamps that you have on your original non-O visa become invalid once you receive the “under consideration” stamp so if you want to travel within those four weeks out of the country you need to get a new re-entry permit.

You're using the wrong terminology, and that's why you're not finding the correct information. You already have the retirement visa. That's what the non-O visa is. There is no more visa. You won't have a visa again after this. That visa was used when you entered Thailand. From now on you will be applying for extensions. An extension does not require 15 days or any amount of days to apply. You can apply on the last day of your permission stamp in your passport (not advised to do so). Retirement extensions are usually given the same day you apply, no need for the 15 days because there is no "under consideration" period.

The 15 days is only needed when you are converting from tourist to a non-O retirement visa (which you already have).