Hey @lauriane,

the user drydoc46 at some point got control over your account and set a withdraw route to himself.

https://steemd.com/tx/2655ec8c02128e0cf5a83ad9daed34d6ef7fcc2b

When you start a Power Down he will get all your STEEM.

Look at this tool by @noblebot to remove the withdraw route.
https://steemit.com/steem/@noblebot/noblebot-is-introducing-a-new-tool.

If you don't trust this web application, move your funds to savings. After the withdraw route got removed change your password.