If you are farming or getting through the early stages, automatic control is good enough to get you through. However, when you get to the more challenging fights, you will need to start using manual movement.

With manual control, you are able to move your unit wherever you wish. You are no longer restricted to simply hitting the attack button to walk up to your target and attack them - you can move up, down, and all around! This is very important as you will need to dodge boss attacks later on.

If your healer is having trouble getting their heals off, you can take manual control of them and move them a safe distance away from enemies before you start casting. This should give them enough breathing room to be able to get a heal off.