An exercise you can do is:
- Play a chord, making sure all the notes are ringing out cleanly.
- Relax your fingers so the notes are muted, but keep them on the strings in the right position.
- Press all your fingers down together at the same time.
- Check all the notes are still ringing out cleanly.
- Repeat.
- Why can't I change chords fast enough?
- How do I get better at switching between chords?
- How fast should my chord changes be?
Why can't I change chords fast enough?
Try setting the tempo with your right hand, keep it steady and at speed, force your left hand to try and make the changes as best you can. It will get better as you practice making changes instead of playing slowly. And don't forget that there is no law that says every chord strum has to sound good.
How do I get better at switching between chords?
Try to keep your fingers movement at a minimum. Keep your fingers as close to the strings as possible when you're changing chords. The less you have to move your fingers, the faster you can make the switch. Practice each chord change slowly.
How fast should my chord changes be?
Slowly build yourself up to 60 changes per minute...then move on. Go slow enough to make clean chords. Speed is secondary and will come naturally as you progress. Three changes per second would be a good speed goal, but you don't have to achieve that before "moving along".