About positions:

I suggest that you try thinking of it this way:

If you put your hand on the fingerboard, you can cover four adjacent frets on each string with your first, second, third and fourth fingers. This is a minor third, e.g., on the sixth string from the first fret, F, F#, G and Ab. If we allow shifting, we can get up to A, which is a major third. On the next string over, the note on the first fret is Bb, which is the fourth of F and by an amazing coincidence, the next note in F maj. after the A under our little finger on the sixth string.

In this position (frets 1 through 5 with a single shift), we can play seven major scales: On the sixth string, the scales starting with the notes F at fret 1, G at fret 3 (with the shift), A at fret 5. Then on the fifth string, Bb at fret 1, C at fret 3 and D at fret 5.
On the fourth string, just Eb at fret 1. That's seven scales.

Now, shift down a fret and do the same thing starting at Gb. We get seven scales again: Gb, Ab and Bb on the sixth string, B Db and Eb on the fifth and E on the fourth.

That's a total of 14 scales, with two duplicates, namely Bb and Eb:

F G A Bb C D Eb
Gb Ab Bb B Db Eb E

Rearranged a leaving out the duplicates:

F Gb G Ab A Bb B C Db D Eb E

That's all there are, since F# and Gb, C# and Db, etc., are the same on the guitar.

So, in a single position, you can play 7 major scales and in the next position you can also play seven major scales and you end up with all twelve of the major scales in any two adjacent positions with no more than a single shift for any of these scales. Isn't that amazing?

But wait, there's more! For a given key, say, C, you can play the major scale in all of these seven forms. Depending on the key, it will be in a different place on the fingerboard, and spread out from low to high.

Many other scales fit in with this pattern and just vary with respect to a few intervals. The natural minor and other modes use exactly the same fingerings but use different tones as the tonic. Some other scales don't fit this pattern, especially symmetrical scales and/or ones that repeat every few frets like the whole-tone, half-whole and whole-half scales.