You do not need to apply for anything...

You will get 60 days visa exemption entry to Thailand each time you enter..

However depending on your passport country you may need a visa before you can enter Vietnam..

@Rod **********

93 countries can now enter Thailand on Visa Excemption for 60 days

@Kenny ****

It also happens to be winter in the Northern Hemisphere as well so plenty of people from Europe, the UK and the parts of the USA escaping for the cold..

There is no such thing as a bad time to visit Thailand...

Some months are better than others for weather but just go and enjoy regardless

Until the immigration officer you are dealing with on the day of entry decides you are no longer a genuine tourist and then refuses to grant entry..

Good luck 👍

@Josh ********

I have never flown that airline so I cannot offer advice..

But I have flown many times from Australia to Thailand with the same airline and only had my first name on the ticket..

However on a different airline flying to Vietnam they insist on having your name exactly as shown on your passport (first and middle name) so you may get to Bangkok and then have problems with connections but it just depends on each airlines policy.

Depends on the airline..

You must leave the country before your visa extension expires..

The safest most reliable method is catch a flight to Cambodia and stay a couple of nights at least and fly back to get another 60 days visa exemption.

Phnom Penh is a great city to spend a few days anyway so look at it like a good opportunity to explore a little of Cambodia at the same time.

You should apply for 3 months visa BEFORE you travel and then start the process for getting bank account set up and retirement visa application

@Sandor *******

That was no doubt noted on your passport records with immigration and enough for the immigration officer to take a closer look at your travel history and become suspicious you are not a genuine tourist.

One small mistake is all it takes..

I think your only option is to apply for a tourist visa before you try entering again..

If you cannot get one then consider Phnom Penh Cambodia as that's an interesting place to visit and long term visa are easier to get if you have money..