I have a 30 page workbook that I use for my daily book keeping. Each page represents a day of the month. It has worked great for years. Recently, something strange has happened. When I start day one of the new month and enter data into sheet 1, whatever I enter into the cells copies to the same cells of each sheet within the workbook. That is causing me to have to delete the data on each sheet within the workbook. Somehow I have accidentally caused everything I input to copy automatically to every sheet. Can someone help?

Thanks in advance.
Corey