First, you will need to go to the Settings Menu.
To access the settings menu, click the Settings Option in the upper right corner (when on landscape)
or in portrait mode, Click your phone's menu button and Click Settings.
You will then be presented with the full Settings Menu
Storage Options > Storage Root
Click on Storage Root will give you the storage options menu where it will show your current storage location and suggested "new" locations (e.g. External SD Card). There is no guarantee of a suggestion. Not all devices will provide them.
I there is no suggestion, or you choose to browse for another location aside from the one suggested, you can. That option will allow you to navigate to different folders of your system.
There is NO standard convention for storage names. Usually the space called "sdcard" is the internal storage. The external storage may be named "extSd" "external1", or something else.. While we really wish that Android would standardize, it is not happening.
You will then have to navigate to your external SD card's root folder (assuming you want to store data to the external card)
Push the button "Choose Folder" to choose the one listed at the top.
DO NOT choose bcnav as the root folder. We create bcnav in the folder you specify automatically, and you'd end up with something like bcnav/bcnav.
What if I think I have found the right folder, but BackCountry Navigator won't let me choose it?
Then it is quite possibly read only. We cannot choose a folder that is read only.
Some idiotic manufacturers have decided to only allow certain privileged apps to have write access to external card, usually ones that are preinstalled. They somehow think you only want to put pictures and music on it. While this is rare, if it does occur, there is absolutely nothing we can do.
What can I do if my manufacturer has restricted the access to this external storage card that I paid for with my own money?
Complain to the manufacturer.
If possible, take the device back to the store for a full refund and tell them why.