You're logged in now, so whatever browser you're using must have your password saved. Logical?
Since you don't seem to have it stored anywhere else, and since you're required to physically type it into your keyboard to change it, you couldn't have changed it. It must still be the same password given to you when you signed up for the account. Right?
So the question is..... did you write down the password on paper, like the signup screen begged you to? Or did you skip that step, assuming it was optional? Even though it lists 7 rules of Steemit, and ALL 7 of those rules are NEVER LOSE YOUR STEEMIT PASSWORD?!
If you skipped the most important part of signup, then unfortunately the best advice I have is don't sign out! : (