What I have done to help with chord changes is first I started out with just two fingers for the chords. I worked my way up to 100 bpm with that.
With the three finger chords I make a chord, slap my leg and make the chord again. I do that over and over. Then I will make a G chord, slap my leg and then make a C chord and do that over and over. It is working for me.
https://www.youtube.com/watch?v=j0he...euPc0H&index=3