How can I extend my Single Entry Tourist visa in Thailand after its initial validity?

Mario Nowakowski You did not have to delete the question.

You have a used Single Entry Tourist visa in your passport which was valid till th 24th of May. Meaning you have to utilize this visa before this date and you did by enter Thailand on 27th Feb 2019.

You got a new rectangle stamp with the entry date of 27 Feb 2019 and a new date 60 days later, quickly counted around 27th April 2019. Please check if I'm correct.

You can visit the Immigration Office before this date to apply for the 30 day Extension of Stay.