As per the YouTube video I am making a series of Neo Soul / RnB Backing tracks in various keys. I have put a keyboard display at the bottom of the screen so people can see the notes of each chord to help them play along. You may or may not notice but not ALL chords are in the given key. Some chords are borrowed chords which are used a lot of the Neo Soul Genre. However it is fine to improvise in the given key only.
Once you are a familiar with the chords and the key, you can try quickly switching scales just for the bar with the borrowed chord. A good example would be the 2nd chord in this video Gb min9. This chord contains the key “Ab”. However Ab is not in the scale of E minor, so hitting Ab in the melody here would sound good.
Many more coming soon.