Hello @wattoo.
It appears you have exposed your private MEMO key as a memo in a recent transfer.
We suggest changing your password before another user can maliciously use it; reading any encrypted messages sent to your account, or pretending to be you on services such as Minnow Booster.
To change your password go to https://steemit.com/change_password and fill out the form.
Click here for more information.