Where do gall bladder symptoms mainly appear in kids?

Same as adults: Gallbladder symptoms include pain (noncramping, nonburning, localized to right-upper or mid-abdomen)+/-nausea+/-vomiting+/-fever. The pain may radiate around to the right upper back+/-shoulder. Symptoms are often precipitated by food, especially fatty/fried foods. An attack will typically last about an hour or longer. Although rare in children, it can occur (esp with obesity or blood disorders).

Gallbladder symptoms: If you mean what symptoms. They typically will have pain in the upper right side of their belly. Frequently it occurs after a higher fat meal or snack. It is unfortunately becoming more common as more kids are overweight. There are some diseases that place kids at risk for developing gallbladder problems.