Go to the bottom of the menu, to System.
Then to Switch Select. Pick which switch you want to use.
Then scroll that switch to 2P for a 2 position or 3P for a 3. F will only do 2. (I think you want 2, not completely sure)
Then use servo horn/linkage adjustments, sub trim and travel on the radio to get proper shifting without binding. Edit: also reverse might help for 2P.