It takes great skill to always have every child in sight. Your back is never to a child (always to a wall) you need to learn to do a task while still being fully aware of each and every child in the room. You can't put your full focus on anything as you NEED to be aware of all.

If you haven't quite mastered that yet then you need to limit what you are doing to circling and managing. It will mean all meals are prepped in the evening, all art supplies are prepped and at the ready etc.

It get's easier with practice but you do need to consciously be fully aware of your surrounds. You need to be one step ahead of each child's actions so you can call out and prevent the majority of incidents.

I would suggest sitting and thinking about where the main issues are arising. Are the crying child in one area of the daycare more so than other areas. If so then figure out how to be more aware of those areas to start. Are there times of the day you are missing more, why and what can you do to limit that.

Good luck!