You can select multiple vias at the same time and change their properties. See Tutorial: Introduction to PCB design with KiCad version 5.1 (Getting Started) section “Updating the pcb with the new limits”
You can select multiple vias at the same time and change their properties. See Tutorial: Introduction to PCB design with KiCad version 5.1 (Getting Started) section “Updating the pcb with the new limits”