Changing your privacy settings and adding locations to an iNaturalist observation is easy in iOS.
To change your privacy, go to the Details page of an observation. This is the area where you identify the organism. If you want to change the privacy on an observation that you already made, just hit Edit.
Once you get to the Details page, choose the Geoprivacy menu, and then select Open, Obscured, or Private. Save your changes and re-synch your observations.
If you have a photo without the geolocation embedded in the file, you can manually add the location. You still have the same choices for privacy.
On the observation Details page, you will see No location. Click through to change it. By default, that’s going to put you in the middle of the Atlantic Ocean, and that’s probably not where you made the observation. In the lower left, you will see a location arrow (circled in pink on the screenshot). If you click that, it will move the location to where you presently are. From there, you can move the crosshairs around until you get to the right spot.