[jaywalk]

You're simply incorrect. If you set the column format to Text it will never convert data to dates, including when you open the file.

[zozbot234]

Great, how do you set a custom column format in a CSV file?

[ryukafalz]

I'm only familiar with LibreOffice and not Excel myself, but: if you want to be sure a column is treated as text in a CSV file, you have LO quote text fields on save, and have it treat quoted fields as text on import. I assume Excel must have similar options.

[rini17]

LibreOffice, on opening of CSV file, always pops an import dialog where you can do this. To keep the column format permanently, save as ods.