Defending Screens and Dribble Handoffs

Our 4th grade team gets confused when defending ball screens, away screens, and dribble hand offs. We give up a lot of easy baskets because of it. Our league is man to man only.

What should we be doing?
Switching on everything?
Going under?

I really don't want to get into hedging at all or even having rules for certain situations, but different rules for others if that makes sense. I think they would be confused in the moment and hesitate and have the same result.

We switch all ball screens and hand offs. When switching, the person that gets screened should get under the screener to stop the roll.

If our players want to switch other screens off the ball... I"m fine with that. When never taught it.
Most our youth girls just started doing that on their own.

Whatever you do, keep it consistent and practice what they'll see in a real game over and over.