What you have to understand, step10, is that a CSV file is a sort of extract of a single worksheet that contains just the text of each cell's value. No formulae, just the results. No formatting, which means no fonts, colors, borders or special output formats, including dates.

Therefore when you read in a CSV, Excel can see only the value, not the way you want it expressed. If you want to save a date format from one session to the next, you have to save the worksheet in one of the formats (using Save As) that isn't text only. That's most of them; the default is .xls[x], and it'll save all that stuff for you. Really CSV is intended only to help you transfer data between Excel and other applications.