Cybersecurity warnings are frequently ignored or misinterpreted by even experienced adults. While studies have been conducted to examine warning design for adults, there is little data to establish recommendations for children. We conducted user studies with 22 children (ages 10-12) and with 22 adults. We compare their risk perception of warning design parameters (signal colors, symbols, words) via card sorting and ranking activities followed by interviews. While our findings suggest similarities in how both groups interpret the design parameters (e.g., red, skull, and fatal convey danger), we also uncovered potential concerns with items currently used as security indicators (e.g., both groups had mixed interpretations of the open lock and police officer symbols). Individual risk perception, particularly for children, appears dependent on personal preferences and experience. Our findings suggest implications and future research directions for the design of cybersecurity warnings for children.