How do I change geolocation of photos in the Photo app?
I do not know a way to edit the location of photos on the iPhone but with El Capitan you can now edit them in the Desktop Photo App:
- select the one or more photos
- press cmdI or use Window -> Info
- check/enter and/or edit the location information under Location
That information is based on the GPS information in the EXIF metadata, and cannot be changed in the Photos app.
If you export the photo to your Desktop, then open it in Preview, you should be able to cmdI and select the 'More Info' tab (the 'i' with a circle around it) and check the 'GPS' tab to see if the information is correct. If you want to change the GPS coordinates, there are a number of third-party tools to do this – but I generally use ExifTool.