Fretboard positions
A shape's name is the solfège syllable of the note at string 6's starting fret. So in any key, each shape only occurs at a handful of frets — the start-fret buttons list exactly the ones that exist. Click any note to hear it.
A shape's name is the solfège syllable of the note at string 6's starting fret. String 6 open is E, which is mi in C major, so the Mi shape can only start at fret 0 or fret 12. The start-fret buttons above only list the frets where this actually happens in the current key.
Changing key shifts every shape together. Switch the key to D major and the Mi shape moves from fret 0 to fret 2 — the other shapes all shift by the same two frets.
The pentatonic scale is just the major scale with fa and si removed, leaving do re mi sol la. In 7-note mode those two notes are marked with hollow green circles so you can see at a glance what pentatonic drops. There are only five shapes — Do, Re, Mi, Sol, La — because Fa and Si's starting notes aren't in the pentatonic scale at all, so they can't anchor a shape.
A major scale's pentatonic and its relative minor's pentatonic are the exact same notes. C major pentatonic = A minor pentatonic — the only difference is which note you treat as home. For a minor-flavored solo, resolve to la.