Need to downgrade to High Sierra from Mojave on the new Macbook Air (2018)

I recently bought a new Macbook air retina and it shipped with Mojave, unfortunately this OS is not compatible with the Qt suite and it makes impossible for me to work as the application is not getting the input for some reasons.

How can I downgrade the OS to High Sierra? I tried restoring the backup of the other Macbook air I use for work (2012 model) but it say it cannot restore a backup from a different device