Where do gall bladder symptoms mainly appear in kids?

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.
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).