Can't login??? Very strange, can someone help..

Hey steemit, my sister just "successfully" made an account on here and says she can't login but is 100% sure she is putting her password in correctly.. does anyone have any tips or reasons why this may be?

Furthermore I can login no problem but when I try to open "steemit chat" (as I was looking for support to help my sister out) and it asks for my account name and password it says either the account name or password is wrong even though I definitely know my account name and password.. what is going on? Any ideas..? Thanks everyone.