What is KHS?
Thank you for posting on the Community.
Since you have mentioned that you have tried all the troubleshooting steps and still unable to login to PowerSchool mobile app. I would suggest you reach out to your school district who should be able to resolve your concern.
Alternatively, you could also reach out to the PowerSchool mobile support team at mobilesupport@powerschool, they should be able to help you resolve your access.