Remember , the scale tells you what sound right together with the arpeggios. Of course you can play almost any notes on the fretboard, but knowing that if the chord is G# for example, the notes are G# C D#, you should try play around these notes. You may stop at these notes, depending on your choice, or for example stop at G, so as a result if the chord is playing G# and you stopped at G, the whole thing sounds like a G#maj7 as G is the maj7th of G#.