Public Function Auto Update Cell From Two Criterias That Match

[benntw]

I have a sheet that people are supposed to update the percentage daily in a horizontal date range daily. My main sheet calculates the current percent complete in cell S6 on sheet "Daily Progress". On that same sheet in C1 is the current date. I'd like to leave this cell a formula equals to Today() so I can test the code. On sheet "Data" I have a range of dates that can change from a short date range to a longer date range from project to project. This range is in Row 2. In Row 4 is my actual percent complete for that day. This needs be populated from S6 on sheet "Daily Progress". Is there a code that will keep the previous dates value and only change the current date's value when you save the workbook ? I have looked up countless public functions to try and figure it out and it is kicking my butt. Thank you.