"I cook by myself."
Translation:나는 혼자 요리합니다.
Isn't that different politeness levels? Can you use 나 with 습니다 politess level?
Actually you can. The politness ending is for raising the listener and using the humble pronoun is for lowering youself. You can choose to raise the listener without needing to lower yourself.
I agree. I know its a thing you technically can so, but I have never heard it in media or in my 4 months I lived in Seoul.
Fix this already please , everytime i make a mistake its not my fault but yours
i use 나는 혼자 요리해요 why is it not correct ?
It means 'alone' or 'by oneself'. It can be used in any levels of formality and politeness.