I don't know what are you doing with your wallet and all this fud about it guys, here all is fine and working well....
To export your private key just go to "Wallet" > "Export private key" that it!

Just install the latest wallet from the official website here > https://github.com/z-classic/zclassic/releases

CHEEERSS  

https://i.imgsafe.org/47fae0988a.jpg