The app will display date & time formats based on the device location:
But if you’re talking about how you see it as you are building, then that’s slightly different: https://docs.glideapps.com/all/reference/components/pickers/date-time#date-formats-and-locales
I believe login timestamps will be in your spreadsheet’s timezone and formatting… but I might have to test that out to see. Let me know if you find otherwise.