Hi there! It sounds like you're having trouble saving your Excel spreadsheet as a CSV file while keeping the date format as YYYY-MM-DD. Here's what you can do:

1. First, make sure that the date column is formatted as YYYY-MM-DD. You mentioned that you've already done this, so great job!
2. Next, go to File Save As and choose "CSV (Comma delimited)" as the file type.
3. In the "Save As" dialog box, click the "Tools" dropdown menu and select "Web Options."
4. In the "Web Options" dialog box, click the "Encoding" tab and select "Unicode (UTF-8)" as the encoding.
5. Click "OK" to close the "Web Options" dialog box.
6. In the "Save As" dialog box, click "Save" to save the file as a CSV.
7. Close the Excel file and open the CSV file in a text editor like Notepad or Editplus.
8. Look for the date column and make sure that the dates are formatted as YYYY-MM-DD.

That should do it! By saving the file as Unicode (UTF-8), you're ensuring that the date format is preserved when you open the CSV file again. Let me know if you have any other questions!