Depending on the version of Excel you are using, the dates values of the exports generated from our Dashboard may not be automatically formatted as dates in Excel.
This can be solved by performing an action that will force the formatting of these data.
1- Select the column in which you have the date values
2- Go to the "Data" Tab
3- Click on "Convert"
4- Select "Fixed width" > Next > Finish
The format should now be switched to a date for all your values.