Expected date format:
MMM DD, YYYY HH:MM AM/PM i.e. Nov 30 2017, 12:00 PM

Change it in the following table

1. Sub-items table
2. Content view > Details Tab > Content details table
3. Content view > Versions Tab > Draft under edit table
4. Content view > Versions Tab > Published version table
5. Content view > Versions Tab > Archived versions table
6. Admin Panel > Content Types > Content/Media/User > Content types table