How to select aspect ratio in kinemaster

how to select aspect ratio in kinemaster Kinmaster is a good 100% youtuber use kinmaster I am use kinemaster Camra oppo a 83 Tripod mobile stand Microphone no use Oppo a 83 good microphone Ap ko kinmaster ???????????https://drive.google.com/file/d/11iINc1CmNI4JNVcj-uF6lLdEo3PLd6pL/view???????????