How to Make Gmail Remember my User ID and Passwords with Safari

I work in marketing and have several Gmail accounts established exclusively for my clients advertising programs that I must access frequently. Until a few days ago, each time I opened any Gmail account the User ID (Gmail address) and password have remained saved and would populate as I entered the first character of the Gmail address I was attempting to open. When a colleague asked me to open her Gmail account during a time when her system was down, I unintentionally clicked "never for this Web site" when Safari asked if I wanted to save her logon information and password. I realize now that I had clicked the wrong option and since that time none of the Gmail accounts are saved requiring that I enter the full address and password each time. I've followed the instructions on the help menu but nothing has worked. I use Safari version 6.0.4 and Mac OSX version 10.7.5. Any suggestions would be appreciated.