@Tony *********
There is no “marriage visa” with which you can live in Thailand permanently.
You can apply for a “one-year extended stay permit based on being married to a Thai wife”, and after being issued it, then EVERY year, you need to apply again
Actually, every “single entry visa” becomes invalid when entering Thailand
Entering Thailand, you get stamped in for a 30-days, 60-days, 90-days or 365-days STAY PERMIT, the length is determined by the “visa class” you are using
After you entered, the visa itself is “used” or “invalid” or “void”. Period.
A "visa" allows you to enter Thailand, and only a "stay permit" allows to stay in Thailand. The “admitted until” stamp in your passport is a stay permit, and the wrongly called “marriage visa” or “retirement visa” which are issued by Immigration, actually are stay permits
You can apply for a “single entry 90-days married to a Thai wife Non-Imm-O visa” in your home country, enter Thailand and then, after you have fulfilled some requirements, apply for the "one-year extension of stay permit based on being married to a Thai wife".
Most people call this a "marriage visa", however a "1-year extension" is not a visa any more, it is a STAY PERMIT.
Immigration in their very bad English calls the extended stay permit a "visa extension", but TECHNICALLY, they don't extend any visa - they extend a stay permit.
A "visa" can technically speaking, not get "extended". A visa is meant for a one-time use
For both the application to the initial "visa" and for the application to the "1-year extension of the stay permit", you will need to fulfill a financial proof.
Which is either a deposit of a minimum of 400.000.- THB in a bank account in your sole name, or a proven monthly income of a minimum of 40.000.- THB.
You alternatively can enter Thailand visa-exempt, get stamped in for 60 days, and apply for the 90-days Non-Imm-O visa on Immigration, under slightly different requirements. This process is called “change of visa type” and you can find its different purposes and requirements on an Immigration website when you google for these words