Outlook.com account is hacked. Changed password twice and used authenticator app but still sending messages.

My outlook.com account is hacked. My account is sending emails to my list of contacts with links in it. I have changed the password twice and turned on the authenticator app but it is still sending spam emails. They don't show up in the sent folder but I get bounced-back emails sent to my junk folder and a friend told me I sent him spam. HELP! What do I need to do to stop this? I have a mac that I use this account on and a Window's phone as well.