What should I do if my non O-A retirement visa does not indicate multiple entry at immigration in Thailand?

The immigration office here isn't gonna stamp ANYTHING in your passport

You're confusing two separate government entities

You got your visa from a thai consulate in your country before you washed up here.

Thai embassies and consulates are run by the Ministry or Foreign Affairs office <- they sell visas OUTSIDE thailand

Thai immigration offices are run by the Immigration division of the Royal Thai Police <- they sell visas/extensions INSIDE thailand

They have abso-tively, posi-lutely NOTHING to do with each other

As I said, if you have an eVisa where they mailed you the PDF, that IS your visa, and you print that paper can carry it in your passport for it's validity. There is no visa sticker, visa stamp etc you can get from immigrations here because you didn't get the VISA here you got it before you came.

All you get when you enter is a small red entry stamp that says Non-OA with an entry date and a date you can stay until.. 😕

I think your e-visa serves as the multi entry part which you show next time you enter.

You PRINT and show the eVisa PDF every time you stamp into the country that PDF is your visa.. It's got all the information on it

Your entry stamp will NEVER show that you have multi-entry or not, it will just say Non-OA and the date you entered and the date you can stay until

All OA visas are multi-entry

Under “No of entry” title it will say multiple if it is.

If it’s a single entry you will have to go to immigration and fill in a form to get a multiple re-entry stamp

Any immigration officer will see that you have a non O-A and know that it is multi entry