Repeatedly being locked out of our emails.

We have been having a great deal of trouble with our hotmail account.  First, we were given a four digit number - supposedly for extra security - then, when we tried to log in with the number, we weren't allowed in.  We thought we had solved things when we requested a passport re-set yesterday and were able to access our emails last night.  However, today we found that we could not get in using the new password and had to change the password again.  Could anyone suggest how we could solve this problem?    Thank you.