You can change the coordinate system associated with a project, provided that more than one coordinate system is active in your configuration.

It's also possible to update the coordinate system for multiple projects at once using the Bulk Update Coordinate Systems tool.

Steps to Change the Coordinate System

1. Open the Project you wish to update.
   1. If you are unsure of the coordinate system, or the which pair of latitude/longitude or easting/northing you want to use, take a snapshot to revert to.
2. Go to the Project tab.
3. Select Project Details.
   
4. Navigate to the Coordinates tab and pick the new coordinate system.
   
   
   
5. Click Save.
   
6. You will then be asked to chose either Easting/Northing or Latitude/Longitude. Which ever one is picked, those values will not be changed and the others will be recalculated.
   If you select the wrong pair, you can revert the process by following the same steps and selecting the old coordinate system.