There are several ways to find the positions, but there are sometimes more than one position that you can play the same passage. In the examples you could play the  passage in several places but  I would look at it as just 2 different positions.  ex 1 is 9Th position.  ex 2 the 14TH position EX. 3 is 12 Th position.  I usually try to find the highest notes within a passage and then  figure out the easiest way to play that passage while thinking of the next move  on the neck. If  I had to play this passage, (examples) and would have to move back down to the lower positions, for lower notes. I would play it in the 9Th position.  If I had move up to notes that would be higher on the neck I might think of playing them in the 12 Th position. Also tone has something to do with it. As you know different strings and positions produce different sounds so you might want to find a position that would sound similar to other notes within a certain part of a song or passage for continuity.



I hope I helped some and did not confuse you even more.