I am learning Quattro Pro X8. Need help with entering dates

I have used Excel for some time and am wanting to use QP.    I have a spreadsheet where I want to enter dates in 3 different ways [month/day;  month/day/year;  day/month/year].     On the surface it is easy, yet when I save the file and then open it, the three displayed dates revert to 1 format and all the dates have been changed.    The only way around this that I have found, is to go to Tools;  Settings; International; here you can set the date style.  When you do, however, all of the existing dates in a spreadsheet are changed to this format.     How can I set the date or where do I set the date to work -- so I can use more than one display.