When I first started using Korean, I had watched a few dramas and I was always confused which thank you I should use. I heard the formal version most often, but also heard the impolite form.
It wasn’t until I studied Korean more that I found out about politeness levels and then it made sense of course.
For saying thank you, there are several ways like most basic phrases in Korean. You have the formal, polite, and informal forms to work with.
Let’s start with the formal version. There are two ways (romanization included):