If you're opening a text file and want a column to stay as text, select text
as the format for that column at the end of the import.

Unfortunately when the file is open it is already too late for doing that!
Here is what happens when I select a column and do Format Cells - Text:
The data that was kept as it was (10/24/2006) stays the same: 10/24/2006.
But the data that got automatically converted (05-01-06) produces a complete
nonsense: 38729

If you want it to import as date, ensure that your Windows Control Panel
Regional Settings match your preferences.

I want to import the data just the way it is, and see my column just the way
I want it to be: MM/DD/YYYY. I do not want it to match my Regional Settings
which I like to keep in a different format. I want Excel to stop acting as it
knows better what I need, but I don't see how to fix it.