"No, thank you."
괜찮습니다 is used to say "no thank you" specifically, not "thank you". It literally means "It's okay" or "I'm fine" etc but in Korea it is also used as "no thanks" in the context of someone offering you something you don't want. In that context 아니요 감사합니다 wouldn't make sense in Korea. They made it confusing by teaching it that way and it seems like they're trying to rectify it now. Hope that helps!
I agree. Theres no excuse for some of the missteps that I too am seeing. I dont want to learn like this, however, it is keeping us on our toes yes? I hopw they fix it. I also have multiple apps to help me learn this language. As well as others. By the way have you ever heard of a man that went by the handle, "loushu"? He was from Ohio, I believe. He was a self taught polyglot!!! You can find him on YouTube. Re: Black man speaks Japanese Loushu , level up videos. Unfortunately, he has past away from a heart condition recently. He has inspired me to keep going. Check him out if you can. I encourage you!!! Take care!! Portland Oregon 26 Aug 2021 Time: 0019
괜찬습니다 (it's okay/I'm okay) can also mean 'no thank you' depending on context. For example if someone offered you a glass of water and you said '괜찬습니다', it would mean you don't want the glass of water. It's similar to in English. If someone said 'Do you want some water?' replying with 'No, I'm okay' would still make sense.
In Korea, 괜찬습니다 is also used as a way to say 'no thank you'. For example, if someone said "Would you like a glass of water?", and you replied with "괜찬습니다", that would be a polite way of saying "No, I don't want a glass of water". It's similar to English. If someone asked "Would you like some water?" and you responded in English with "No, I'm okay", it would still make sense.