This is because you are letting ArcMap decide the break points for your classification symbology. Take the layer with the highest value, and manually set the break points you want for all layers. When you have that configured, either save that as a lyr file and then import it for the symbology of the other layers, or choose import >> and select that first layer. This will keep the same class breaks, descriptions, and size for all your features.
Regards,
Jim