Can I switch between the front and back camera to read QR barcodes with the ServiceNow mobile app?
At this point in time, only the main (back) camera on a phone is used by the ServiceNow mobile app to read QR barcodes. There is no current plan to also extend this functionality to the front camera on mobile phones.
If this is a feature that you would like to see implemented, you can fill out a enhancement request via HI:
Self-Service > Enhancement Requests > Open an Enhancement Request