I can’t see the transaction history that Yoroi currently delegates to the pool.
Also, even if I try to move to another pool, the fee(-0.8) is not displayed and it keeps failing.
Is there a solution?
This worked for me:
Delete yoroi chrome extension
Re-install and and restore your wallet with the 15 seed words.
Transactions that did not truly fail will be displayed, and you should have full functionality.
Yes, so that last green transaction is where you are staking. Unfortunately, I don’t know of an easy way to tell by the transaction ID which pool that is. That failed transaction you did today may actually go through, give it a little time.
If the transaction is normal, the fee should be displayed as -0.8.
But after 29th, my delegation fee is all my amounts, and they’re all failing.
Is it not possible to transfer to another wallet on the current testnet?
At this point I have no Ideas. Best of luck to you my friend in Korea 
Oh, try this. I find that the network is “more in sync” a few minutes after the end of an epoch. Try to re-delegate then.
Download Daedalus, put your 15 word passphrase into that and see if its correct there.
I have mine in ITN Daedulus and Yoroi ITN, in Daedulus its correct but in Yoroi ITN I have the same issue as you.