Yobit have bad reputation since acouple years so i never use it, and for Cryptopia according to their update in twitter they will reopen the exchange in 2 days on monday. There are alot of crypto exchange that much better than Yobit, Use crypto exchange that has good reputation and friendly customer support, like Binance, Kucoin, Gate.io, Bitmax etc, all these exchange provide customer support via official telegram group.
I really wonder why people still uses yobit, crytopia and other shit exchanges when there are so many reputed exchanges like Binance / Bittrex available?
Unless you want to invest in the coins which is only available in these small exchanges, there is no reason to use these exchanges for trading. Even if you have to use, just trade and withdraw all the funds from them. Never keep any funds in these exchanges for a longer duration of time.