There could be times when the GPS you are using will not provide you with accurate enough location information. When this happens, changing the location of a record manually on your mobile device is an easy way to assure quality field data. To do this, select the cross-hair icon from the edit record screen on your mobile device. Once one the set location page, you can move the cross-hair on the map to the desired location and then save the new location.
Additionally, you can also manually type in the coordinates if you are using an external GPS that is not paired with your device. Simply tap on the coordinates displayed on the set location page to be able to manually enter in the coordinates.
Android article on setting the location.
iOS article on setting the location.