Kurt was right handed not Left handed.
There seems to be a perpetuation of the myth that he was somehow left handed. Type in 'kurt cobain was right handed' and the message blob at the top says, incorrectly, that he was a lefty.
Kurt did literally everything with his right hand. He wrote with his right hand, in Montage of Heck with reel footage of him as a toddler, he would play toys with his right hand (while holding guitar with his left). In an interview by Nardwuar, he was holding his slice of pizza with his right hand. Or the poster with him holding a gun with his right hand. He would use his right hand for pretty much everything, even writing.
The only thing he did with his left hand was literally playing the guitar. That's it.
go look it up. he's a full-blown rightie. Which is too bad. he'd be cooler if he were a fellow lefty. oh well.