There is besically no right or wrong way to mount a Saphe One and Saphe One+.
We recommend that you mounting it so that you can clearly see it and reach the buttons on it.
Our recommendations are either in the windshield or on the dashboard, and if you mount it vertically we recommend that the buttons face upwards.
On the backside of the Saphe One / Saphe One+, there are som adhesive pads to mount it with.
Here is a small video of how to mount them: