Copper exports data in a MM/DD/YYYY format. Here are steps to convert the date to DD/MM/YYYY via Google sheets.
1. Go to Copper -> Settings -> Export data
2. Go to your email and download the report
3. Go to Google sheets https://docs.google.com/spreadsheets/u/0
4. Create a new blank spreadsheet
5. Go to File -> Import
6. Import in the file
7. Highlight the column with the dates you want to change
8. Select Format -> Number -> Date
9. Then select Format -> Number -> Date -> More Formats -> More date and time formats...
10. Put your cursor/mouse at the end of where it says year and delete everything
So it looks like this:
11. Click the arrow to the right of the box so it looks like this
12. Select Day and type a / behind it
13. Then add month/year
14. Click "Apply"
15. You should see the dates change to your preferred format.