because YoBit is an exchange you can buy/sell BSC at YoBit, that's what you do on an exchange.
What you do on an exchange is deposit your BSC to sell them, and then withdraw your BSC to your own wallet.
You can't do any of that at YoBit, because their BSC wallet has been offline since last year.
But you already know the difference between on-blockchain transactions and entries in a private exchange's database:
you need to talk to exchange. no-one else can help you if the coins are not on the blockchain