The floor height in PeriopSim VR is directed by the Windows Mixed Reality Portal. The floor height can be adjusted using the "Room Adjustment" app or "Floor Adjustment" app from within the Mixed Reality Portal house.
If Mixed Reality Portal is not running plugin your Mixed Reality headset and the Portal will startup. Ensure at least one controller is enabled.
Press the Windows button on the controller to open the Start Menu. (If a sideways menu opens with a "House" button in the middle, aim the controller on this button and click on it to return to the Mixed Reality Portal house first.) Click on the "All Apps" then click on the down arrow until you find the "Room Adjustment" or "Floor Adjustment" app. The name of the app depends on the version of Windows 10 that is installed.
A 3D object will be attached to your controller. Place this object somewhere in your house by pulling the trigger. When the pointer returns, aim at the object and click the trigger to launch the app.
Follow the directions in the app to adjust the floor height. It is recommended to place one controller on the floor and adjust the height until the floor is just bellow the controller. Click on the floating gem to save the adjustments and return to the house.
Launching PeriopSim VR from the desktop will now have the correct height.