Glad you're back! I'm sorry to hear that your hard earned steem was stolen by someone. If you noticed there's actually a new wallet system, when you clicked the wallet you'll be directed to steemitwallet.com/@yourusername. Take the chance to change your keys and always note to store you're master password somewhere safe and try to NEVER use it. Storing it offline would be the best.

Well, I'm not really good with words so these posts from @llfarms and @andrarchy might be of help.

https://steemit.com/steem/@steemitblog/steem-basics-understanding-private-keys-part-1

https://steemit.com/steem/@llfarms/normie-talk-new-steemit-wallet-change-or-how-does-it-work-now