You are not actually "setting" a password, you should be "entering" your current ACTIVE KEY to log into the wallet site. This will not reset/create new keys. If you do NOT have your ACTIVE KEY, you can use your MASTER KEY in the prompt that pops up on Steemitwallet.com and it will let you download all your keys in the form of a PDF file. This also will NOT reset or change any current keys you have.