I take it as "change notes here and there" refers to rearranging the notes of a scale to convert minor scale into a major scale?
If so , Well I don't think what your friend said about by changing the notes here and there , you can convert a minor pentatonic scale into a major scale because every scale has it's own notes for both the major and minor scale.
I guess the reason why most people especially the guitarists use the minor pentatonic scale only is because it sounds "nice"? :lol:
For example :
C Major pentatonic scale : C , D , E , G , A , C
C Minor Pentatonic scale : C , Db , Eb , G , Ab , C ( I hope I'm correct)
By rearranging the notes to convert a C Minor pentatonic scale into a C Major pentatonic scale , I doubt that is possible....
You can play a minor scale in a major song but you need to know which major and minor scales are inter-related to each other in terms of the number of flats/sharps they have.
If the song is in G major (1 sharp) then you can play a E minor scale (1 sharp) in it...
If a song is in D major (2 sharps) then you can play a B minor scale (2 sharps) in it etc
You just need to know which minor scale shares the same number of sharps/flats as the major scale.